Linux From Scratch

Version 6.1.1

GerardBeekmans

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8. Making the LFS System Bootable

9. The End

IV. Appendices

Preface

1. Foreword

My adventures in Linux began in 1998 when I downloaded and
installed my first distribution. After working with it for a
while, I discovered issues I definitely would have liked to see
improved upon. For example, I didn't like the arrangement of the
bootscripts or the way programs were configured by default. I
tried a number of alternative distributions to address these
issues, yet each had its pros and cons. Finally, I realized that
if I wanted full satisfaction from my Linux system, I would have
to build my own from scratch.

What does this mean? I resolved not to use pre-compiled packages
of any kind, nor CD-ROMs or boot disks that would install basic
utilities. I would use my current Linux system to develop my own
customized system. This “perfect” Linux system would then have the
strengths of various systems without their associated weaknesses.
In the beginning, the idea was rather daunting, but I remained
committed to the idea that a system could be built that would
conform to my needs and desires rather than to a standard that
just did not fit what I was looking for.

After sorting through issues such as circular dependencies and
compile-time errors, I created a custom-built Linux system that
was fully operational and suitable to individual needs. This
process also allowed me to create compact and streamlined Linux
systems which are faster and take up less space than traditional
operating systems. I called this system a Linux From Scratch
system, or an LFS system for short.

As I shared my goals and experiences with other members of the
Linux community, it became apparent that there was sustained
interest in the ideas set forth in my Linux adventures. Such
custom-built LFS systems serve not only to meet user
specifications and requirements, but also serve as an ideal
learning opportunity for programmers and system administrators to
enhance their Linux skills. Out of this broadened interest, the
Linux From Scratch Project was born.

This Linux From Scratch
book provides readers with the background and instruction to
design and build custom Linux systems. This book highlights the
Linux from Scratch project and the benefits of using this system.
Users can dictate all aspects of their system, including
directory layout, script setup, and security. The resulting
system will be compiled completely from the source code, and the
user will be able to specify where, why, and how programs are
installed. This book allows readers to fully customize Linux
systems to their own needs and allows users more control over
their system.

I hope you will have a great time working on your own LFS system,
and enjoy the numerous benefits of having a system that is truly
your own.

--
Gerard Beekmans
gerard AT linuxfromscratch D0T org

2. Audience

There are many reasons why somebody would want to read this book.
The principal reason is to install a Linux system from the source
code. A question many people raise is, “why go through all the hassle of manually building a
Linux system from scratch when you can just download and install
an existing one?” That is a good question and is the
impetus for this section of the book.

One important reason for LFS's existence is to help people learn
how a Linux system works from the inside out. Building an LFS
system helps demonstrate what makes Linux tick, and how things
work together and depend on each other. One of the best things
that this learning experience provides is the ability to
customize Linux to your own tastes and needs.

A key benefit of LFS is that it allows users to have more control
over the system without relying on someone else's Linux
implementation. With LFS, you are in the driver's seat and
dictate every aspect of the system, such as the directory layout
and bootscript setup. You also dictate where, why, and how
programs are installed.

Another benefit of LFS is the ability to create a very compact
Linux system. When installing a regular distribution, one is
often forced to include several programs which are probably never
used. These programs waste disk space, or worse, CPU cycles. It
is not difficult to build an LFS system of less than 100
megabytes (MB), which is substantially smaller than the majority
of existing installations. Does this still sound like a lot of
space? A few of us have been working on creating a very small
embedded LFS system. We successfully built a system that was
specialized to run the Apache web server with approximately 8MB
of disk space used. Further stripping could bring this down to 5
MB or less. Try that with a regular distribution! This is only
one of the many benefits of designing your own Linux
implementation.

We could compare Linux distributions to a hamburger purchased at
a fast-food restaurant—you have no idea what might be in
what you are eating. LFS, on the other hand, does not give you a
hamburger. Rather, LFS provides the recipe to make the exact
hamburger desired. This allows users to review the recipe, omit
unwanted ingredients, and add your own ingredients to enhance the
flavor of the burger. When you are satisfied with the recipe,
move on to preparing it. It can be made to exact
specifications—broil it, bake it, deep-fry it, or barbecue
it.

Another analogy that we can use is that of comparing LFS with a
finished house. LFS provides the skeletal plan of a house, but it
is up to you to build it. LFS maintains the freedom to adjust
plans throughout the process, customizing it to the user's needs
and preferences.

An additional advantage of a custom built Linux system is
security. By compiling the entire system from source code, you
are empowered to audit everything and apply all the security
patches desired. It is no longer necessary to wait for somebody
else to compile binary packages that fix a security hole. Unless
you examine the patch and implement it yourself, you have no
guarantee that the new binary package was built correctly and
adequately fixes the problem.

The goal of Linux From Scratch is to build a complete and usable
foundation-level system. Readers who do not wish to build their
own Linux system from scratch may not benefit from the
information in this book. If you only want to know what happens
while the computer boots, we recommend the “From Power Up To Bash Prompt” HOWTO located
at http://axiom.anu.edu.au/~okeefe/p2b/
or on The Linux Documentation Project's (TLDP) website at
http://www.tldp.org/HOWTO/From-PowerUp-To-Bash-Prompt-HOWTO.html.
The HOWTO builds a system which is similar to that of this book,
but it focuses strictly on creating a system capable of booting
to a BASH prompt. Consider your objective. If you wish to build a
Linux system while learning along the way, then this book is your
best choice.

There are too many good reasons to build your own LFS system to
list them all here. This section is only the tip of the iceberg.
As you continue in your LFS experience, you will find the power
that information and knowledge truly bring.

3. Prerequisites

Building an LFS system is not a simple task. It requires a
certain level of existing knowledge of Unix system administration
in order to resolve problems, and correctly execute the commands
listed. In particular, as an absolute minimum, the reader should
already have the ability to use the command line (shell) to copy
or move files and directories, list directory and file contents,
and change the current directory. It is also expected that the
reader has a reasonable knowledge of using and installing Linux
software.

Because the LFS book assumes at
least this basic level of skill, the various LFS
support forums are unlikely to be able to provide you with much
assistance; you will find that your questions regarding such
basic knowledge will likely go unanswered, or you will simply be
referred to the LFS essential pre-reading list.

Before building an LFS system, we recommend reading the following
HOWTOs:

This is an LFS Hint written specifically for users new to
Linux. It includes a list of links to excellent sources of
information on a wide range of topics. Anyone attempting to
install LFS should have an understanding of many of the
topics in this hint.

4. Host
System Requirements

The host must be running at least a 2.6.2 kernel compiled with
GCC-3.0 or higher. There are two main reasons for this
requirement. First, the Native POSIX Threading Library (NPTL)
test suite will segfault if the host's kernel has not been
compiled with GCC-3.0 or a later version. Second, the 2.6.2 or
later version of the kernel is required for the use of Udev. Udev
creates devices dynamically by reading from the sysfs file system. However, support for this
filesystem has only recently been implemented in most of the
kernel drivers. We must be sure that all critical system devices
get created properly.

In order to determine whether the host kernel meets the
requirements outlined above, run the following command:

If the results of the above command do not state that the host
kernel is either 2.6.2 (or later), or that it was not compiled
using a GCC-3.0 (or later) compiler, one will need to be
installed. There are two methods you can take to solve this.
First, see if your Linux vendor provides a 2.6.2 (or later)
kernel package. If so, you may wish to install it. If your vendor
doesn't offer a 2.6.2 (or later) kernel package, or you would
prefer not to install it, then you can compile a 2.6 kernel
yourself. Instructions for compiling the kernel and configuring
the boot loader (assuming the host uses GRUB) are located in
Chapter 8. This second option can
also be seen as a gauge of your current Linux skills. If this
second requirement is too steep, then the LFS book will not
likely be much use to you at this time.

5. Typography

To make things easier to follow, there are a few typographical
conventions used throughout this book. This section contains some
examples of the typographical format found throughout Linux From
Scratch.

./configure --prefix=/usr

This form of text is designed to be typed exactly as seen unless
otherwise noted in the surrounding text. It is also used in the
explanation sections to identify which of the commands is being
referenced.

install-info: unknown option '--dir-file=/mnt/lfs/usr/info/dir'

This form of text (fixed-width text) shows screen output,
probably as the result of commands issued. This format is also
used to show filenames, such as /etc/ld.so.conf.

Emphasis

This form of text is used for several purposes in the book. Its
main purpose is to emphasize important points or items.

This format is used for hyperlinks both within the LFS community
and to external pages. It includes HOWTOs, download locations,
and websites.

cat > $LFS/etc/group << "EOF"
root:x:0:
bin:x:1:
......
EOF

This format is used when creating configuration files. The first
command tells the system to create the file $LFS/etc/group from whatever is typed on the
following lines until the sequence end of file (EOF) is
encountered. Therefore, this entire section is generally typed as
seen.

[REPLACED TEXT]

This format is used to encapsulate text that is not to be typed
as seen or copied-and-pasted.

passwd(5)

This format is used to refer to a specific manual page
(hereinafter referred to simply as a “man” page). The number inside parentheses
indicates a specific section inside of man. For example, passwd has two man pages. Per LFS
installation instructions, those two man pages will be located at
/usr/share/man/man1/passwd.1 and
/usr/share/man/man5/passwd.5. Both man
pages have different information in them. When the book uses
passwd(5) it is specifically referring
to /usr/share/man/man5/passwd.5.
man passwd will
print the first man page it finds that matches
“passwd”, which will be
/usr/share/man/man1/passwd.1. For this
example, you will need to run man 5
passwd in order to read the specific page being
referred to. It should be noted that most man pages do not have
duplicate page names in different sections. Therefore,
man [program name] is
generally sufficient.

6. Structure

This book is divided into the following parts.

6.1. Part I - Introduction

Part I explains a few important notes on how to proceed with
the LFS installation. This section also provides
meta-information about the book.

6.2. Part II - Preparing for the Build

Part II describes how to prepare for the building
process—making a partition, downloading the packages, and
compiling temporary tools.

6.3. Part III - Building the LFS System

Part III guides the reader through the building of the LFS
system—compiling and installing all the packages one by
one, setting up the boot scripts, and installing the kernel.
The resulting Linux system is the foundation on which other
software can be built to expand the system as desired. At the
end of this book, there is an easy to use reference listing all
of the programs, libraries, and important files that have been
installed.

7. Errata

The software used to create an LFS system is constantly being
updated and enhanced. Security warnings and bug fixes may become
available after the LFS book has been released. To check whether
the package versions or instructions in this release of LFS need
any modifications to accommodate security vulnerabilities or
other bug fixes, please visit http://www.linuxfromscratch.org/lfs/errata/6.1.1/
before proceeding with your build. You should note any changes
shown and apply them to the relevant section of the book as you
progress with building the LFS system.

Part I. Introduction

Table of Contents

1. Introduction

Chapter 1. Introduction

1.1. How to Build an LFS System

The LFS system will be built by using a previously installed
Linux distribution (such as Debian, Mandrake, Red Hat, or
SuSE). This existing Linux system (the host) will be used as a
starting point to provide necessary programs, including a
compiler, linker, and shell, to build the new system. Select
the “development” option
during the distribution installation to be able to access these
tools.

As an alternative to installing an entire separate distribution
onto your machine, you may wish to use the Linux From Scratch
LiveCD. The CD works well as a host system, providing all the
tools you need to successfully follow the instructions in this
book. Additionally, it contains all the source packages,
patches and a copy of this book. So once you have the CD, no
network connection or additional downloads are necessary. For
more information about the LFS LiveCD or to download a copy,
visit http://www.linuxfromscratch.org/livecd/.

Chapter 2 of this book
describes how to create a new Linux native partition and file
system, the place where the new LFS system will be compiled and
installed. Chapter 3
explains which packages and patches need to be downloaded to
build an LFS system and how to store them on the new file
system. Chapter 4 discusses
the setup for an appropriate working environment. Please read
Chapter 4 carefully as it
explains several important issues the developer should be aware
of before beginning to work through Chapter 5 and beyond.

Chapter 5 explains the
installation of a number of packages that will form the basic
development suite (or toolchain) which is used to build the
actual system in Chapter
6. Some of these packages are needed to resolve circular
dependencies—for example, to compile a compiler, you need
a compiler.

Chapter 5 also shows the
user how to build a first pass of the toolchain, including
Binutils and GCC (first pass basically means these two core
packages will be re-installed a second time). The next step is
to build Glibc, the C library. Glibc will be compiled by the
toolchain programs built in the first pass. Then, a second pass
of the toolchain will be built. This time, the toolchain will
be dynamically linked against the newly built Glibc. The
remaining Chapter 5
packages are built using this second pass toolchain. When this
is done, the LFS installation process will no longer depend on
the host distribution, with the exception of the running
kernel.

In Chapter 6, the full
LFS system is built. The chroot (change root) program is used
to enter a virtual environment and start a new shell whose root
directory will be set to the LFS partition. This is very
similar to rebooting and instructing the kernel to mount the
LFS partition as the root partition. The system does not
actually reboot, but instead chroot's because creating a bootable
system requires additional work which is not necessary just
yet. The major advantage is that “chrooting” allows the builder to continue
using the host while LFS is being built. While waiting for
package compilation to complete, a user can switch to a
different virtual console (VC) or X desktop and continue using
the computer as normal.

To finish the installation, the LFS-Bootscripts are set up in
Chapter 7, and the kernel
and boot loader are set up in Chapter 8. Chapter 9 contains information on
furthering the LFS experience beyond this book. After the steps
in this book have been implemented, the computer will be ready
to reboot into the new LFS system.

This is the process in a nutshell. Detailed information on each
step is discussed in the following chapters and package
descriptions. Items that may seem complicated will be
clarified, and everything will fall into place as the reader
embarks on the LFS adventure.

1.2. Changelog

This is version 6.1.1 of the Linux From Scratch book, dated
November 30, 2005. If this book is more than six months old, a
newer and better version is probably already available. To find
out, please check one of the mirrors via http://www.linuxfromscratch.org/.

Below is a list of changes made since the previous release of
the book. First a summary, then a detailed log.

Upgraded to:

Perl 5.8.7

Zlib 1.2.3

Added:

binutils-2.15.94.0.2.2-gcc4-1.patch

bzip2-1.0.3-install_docs-1.patch

bzip2-1.0.3-bzgrep_security-1.patch

glibc-2.3.4-rtld_search_dirs-1.patch

glibc-2.3.4-tls_assert-1.patch

texinfo-4.8-tempfile_fix-1.patch

util-linux-2.12q-umount_fix-1.patch

vim-6.3-security_fix-2.patch

Removed:

zlib-1.2.2-security_fix-1.patch;

November 30, 2005 [matt]: LFS-6.1.1 release.

November 24, 2005 [matt]: LFS-6.1.1-pre2 release.

November 24, 2005 [matt]: Fix an issue with Glibc that
prevents some programs (including OpenOffice.org) from
running.

November 18, 2005 [manuel]: Fixed the unpack of the
module-init-tools-testsuite package.

November 18, 2005 [manuel]: PDF fixes.

November 17, 2005 [matt]: LFS-6.1.1-pre1 release.

November 12, 2005 [matt]: Improve the heuristic for
determining a locale that is supported by both Glibc and
packages outside LFS (bug 1642). Many thanks to Alexander
Patrakov for highlighting the numerous issues and for
reviewing the various suggested fixes.

November 12, 2005 [matt]: Omit running Bzip2's testsuite
as a separate step, as make runs it automatically (bug
1652).

November 7, 2005 [matt]: Stop Udev from killing udevd
processes on the host system (fixes bug 1651). Thanks to
Alexander Patrakov for the report and the fix.

November 5, 2005 [matt]: Add a note to the toolchain
sanity check in chapter 5 to explain that if TCL fails to
build, it's an indication of a broken toolchain (bug
1581).

October 23, 2005 [manuel]: Added Bash documentation
installation. Added notes about libiconv and Cracklib.
Fixed the installation of Sed documentation. Replaced a
patch for IPRoute2 by a sed command.

October 19, 2005 [manuel]: Updated the acknowledgements
to current trunk version. Ported some redaction changes
in preface and chapter01 pages. Moved chapter02 to part
II. Added -v switches. Ported several typos and redaction
fixes from trunk.

October 19, 2005 [manuel]: Updated the stylesheets,
Makefile and related files to current trunk versions.

October 15, 2005 [matt]: Use an updated version of the
Udev rules file (fixes bug 1639).

October 15, 2005 [matt]: Add a cdrom group as required by
the Udev rules file

October 14th, 2005 [ken]: Added a patch to allow binutils
to be built from a host running gcc-4, updated glibc
instructions for the rtld patch, updated space/time for
perl and zlib.

October 14th, 2005 [matt]: Added a patch to fix a
security vulnerability in util-linux.

October 14th, 2005 [ken]: Update packages and patches in
the changelog to only reflect changes since 6.1. Update
zlib.

October 13th, 2005 [ken]: Fix known errors in lists of
installed files and bump the perl version.

1.3. Resources

1.3.1. FAQ

If during the building of the LFS system you encounter any
errors, have any questions, or think there is a typo in the
book, please start by consulting the Frequently Asked
Questions (FAQ) that is located at http://www.linuxfromscratch.org/faq/.

1.3.2. Mailing Lists

The linuxfromscratch.org server hosts a
number of mailing lists used for the development of the LFS
project. These lists include the main development and support
lists, among others. If the FAQ does not solve the problem
you are having, the next step would be to search the mailing
lists at http://www.linuxfromscratch.org/search.html.

1.3.3. News Server

The mailing lists hosted at linuxfromscratch.org are also accessible via the
Network News Transfer Protocol (NNTP) server. All messages
posted to a mailing list are copied to the corresponding
newsgroup, and vice versa.

The news server is located at news.linuxfromscratch.org.

1.3.4. IRC

Several members of the LFS community offer assistance on our
community Internet Relay Chat (IRC) network. Before using
this support, please make sure that your question is not
already answered in the LFS FAQ or the mailing list archives.
You can find the IRC network at irc.linuxfromscratch.org. The support channel is
named #LFS-support.

1.3.5. References

1.3.6. Mirror Sites

The LFS project has a number of world-wide mirrors to make
accessing the website and downloading the required packages
more convenient. Please visit the LFS website at http://www.linuxfromscratch.org/mirrors.html
for a list of current mirrors.

1.3.7. Contact Information

Please direct all your questions and comments to one of the
LFS mailing lists (see above).

We also have a wonderful LFS community that is willing to offer
assistance through the mailing lists and IRC (see the Section 1.3,
“Resources” section of this book). However, we
get several support questions everyday and many of them can be
easily answered by going to the FAQ and by searching the
mailing lists first. So for us to offer the best assistance
possible, you need to do some research on your own first. That
allows us to focus on the more unusual support needs. If your
searches do not produce a solution, please include all relevant
information (mentioned below) in your request for help.

1.4.1. Things to Mention

Apart from a brief explanation of the problem being
experienced, the essential things to include in any request
for help are:

The version of the book being used (in this case 6.1.1)

The host distribution and version being used to create
LFS

The package or section the problem was encountered in

The exact error message or symptom being received

Note whether you have deviated from the book at all

Note

Deviating from this book does not mean that we will not help
you. After all, LFS is about personal preference. Being
upfront about any changes to the established procedure
helps us evaluate and determine possible causes of your
problem.

1.4.2. Configure Script Problems

If something goes wrong while running the
configure
script, review the config.log file.
This file may contain errors encountered during
configure which
were not printed to the screen. Include the relevant lines if you need to ask
for help.

1.4.3. Compilation Problems

Both the screen output and the contents of various files are
useful in determining the cause of compilation problems. The
screen output from the configure script and the
make run can be
helpful. It is not necessary to include the entire output,
but do include enough of the relevant information. Below is
an example of the type of information to include from the
screen output from make:

This is not enough information to properly diagnose the
problem because it only notes that something went wrong, not
what went wrong. The
entire section, as in the example above, is what should be
saved because it includes the command that was executed and
the associated error message(s).

Chapter 2. Preparing a
New Partition

2.1. Introduction

In this chapter, the partition which will host the LFS system
is prepared. We will create the partition itself, create a file
system on it, and mount it.

2.2. Creating a New
Partition

Like most other operating systems, LFS is usually installed on
a dedicated partition. The recommended approach to building an
LFS system is to use an available empty partition or, if you
have enough unpartitioned space, to create one. However, an LFS
system (in fact even multiple LFS systems) may also be
installed on a partition already occupied by another operating
system and the different systems will co-exist peacefully. The
document http://www.linuxfromscratch.org/hints/downloads/files/lfs_next_to_existing_systems.txt
explains how to implement this, whereas this book discusses the
method of using a fresh partition for the installation.

A minimal system requires a partition of around 1.3 gigabytes
(GB). This is enough to store all the source tarballs and
compile the packages. However, if the LFS system is intended to
be the primary Linux system, additional software will probably
be installed which will require additional space (2-3 GB). The
LFS system itself will not take up this much room. A large
portion of this requirement is to provide sufficient free
temporary storage. Compiling packages can require a lot of disk
space which will be reclaimed after the package is installed.

Because there is not always enough Random Access Memory (RAM)
available for compilation processes, it is a good idea to use a
small disk partition as swap space. This is used by the kernel
to store seldom-used data and leave more memory available for
active processes. The swap partition for an LFS system can be
the same as the one used by the host system, in which case it
is not necessary to create another one.

Start a disk partitioning program such as cfdisk or fdisk with a command line option
naming the hard disk on which the new partition will be
created—for example /dev/hda
for the primary Integrated Drive Electronics (IDE) disk. Create
a Linux native partition and a swap partition, if needed.
Please refer to cfdisk(8) or
fdisk(8) if you do not yet know how
to use the programs.

Remember the designation of the new partition (e.g., hda5). This book will refer to this as the LFS
partition. Also remember the designation of the swap partition.
These names will be needed later for the /etc/fstab file.

2.3. Creating a File
System on the Partition

Now that a blank partition has been set up, the file system can
be created. The most widely-used system in the Linux world is
the second extended file system (ext2), but with newer
high-capacity hard disks, journaling file systems are becoming
increasingly popular. We will create an ext2 file system. Build
instructions for other file systems can be found at http://www.linuxfromscratch.org/blfs/view/svn/postlfs/filesystems.html.

To create an ext2 file system on the LFS partition, run the
following:

mke2fs -v /dev/[xxx]

Replace [xxx] with the
name of the LFS partition (hda5 in
our previous example).

Note

Some host distributions use custom features in their
filesystem creation tools (e2fsprogs). This can cause
problems when booting into your new LFS in Chapter 9, as
those features will not be supported by the LFS-installed
e2fsprogs; you will get an error similar to
“unsupported filesystem features,
upgrade your e2fsprogs”. To check if your host
system uses custom enhancements, run the following command:

debugfs -R feature /dev/[xxx]

If the output contains features other than: dir_index;
filetype; large_file; resize_inode or sparse_super then
your host system may have custom enhancements. In that
case, to avoid later problems, you should compile the stock
e2fsprogs package and use the resulting binaries to
re-create the filesystem on your LFS partition:

If a swap partition was created, it will need to be initialized
for use by issuing the command below. If you are using an
existing swap partition, there is no need to format it.

mkswap -v /dev/[yyy]

Replace [yyy] with the
name of the swap partition.

2.4. Mounting the New Partition

Now that a file system has been created, the partition needs to
be made accessible. In order to do this, the partition needs to
be mounted at a chosen mount point. For the purposes of this
book, it is assumed that the file system is mounted under
/mnt/lfs, but the directory choice is
up to you.

Choose a mount point and assign it to the LFS environment variable by running:

export LFS=/mnt/lfs

Next, create the mount point and mount the LFS file system by
running:

mkdir -pv $LFS
mount -v /dev/[xxx] $LFS

Replace [xxx] with the
designation of the LFS partition.

If using multiple partitions for LFS (e.g., one for / and another for /usr), mount them using:

Ensure that this new partition is not mounted with permissions
that are too restrictive (such as the nosuid, nodev, or noatime
options). Run the mount command without any parameters
to see what options are set for the mounted LFS partition. If
nosuid, nodev, and/or noatime are set, the partition will
need to be remounted.

Now that there is an established place to work, it is time to
download the packages.

Chapter 3. Packages
and Patches

3.1. Introduction

This chapter includes a list of packages that need to be
downloaded for building a basic Linux system. The listed
version numbers correspond to versions of the software that are
known to work, and this book is based on their use. We highly
recommend not using newer versions because the build commands
for one version may not work with a newer version. The newest
package versions may also have problems that require
work-arounds. These work-arounds will be developed and
stabilized in the development version of the book.

Downloaded packages and patches will need to be stored
somewhere that is conveniently available throughout the entire
build. A working directory is also required to unpack the
sources and build them. $LFS/sources
can be used both as the place to store the tarballs and patches
and as a working directory. By using this directory, the
required elements will be located on the LFS partition and will
be available during all stages of the building process.

To create this directory, execute, as user root, the following command before
starting the download session:

mkdir -v $LFS/sources

Make this directory writable and sticky. “Sticky” means that even if multiple users
have write permission on a directory, only the owner of a file
can delete the file within a sticky directory. The following
command will enable the write and sticky modes:

Note

File (4.13) may no longer be available at the
listed location. The site administrators of the
master download location occasionally remove older
versions when new ones are released. An alternative
download location that may have the correct version
available can also be found at: http://www.linuxfromscratch.org/lfs/download.html#ftp.

Note

Shadow (4.0.9) may no longer be available at the
listed location. The site administrators of the
master download location occasionally remove older
versions when new ones are released. An alternative
download location that may have the correct version
available cat also be found at: http://www.linuxfromscratch.org/lfs/download.html#ftp.

3.3. Needed Patches

In addition to the packages, several patches are also required.
These patches correct any mistakes in the packages that should
be fixed by the maintainer. The patches also make small
modifications to make the packages easier to work with. The
following patches will be needed to build an LFS system:

In addition to the above required patches, there exist a number
of optional patches created by the LFS community. These
optional patches solve minor problems or enable functionality
that is not enabled by default. Feel free to peruse the patches
database located at http://www.linuxfromscratch.org/patches/
and acquire any additional patches to suit the system needs.

Chapter 4. Final
Preparations

4.1. About $LFS

Throughout this book, the environment variable LFS will be used several times. It is paramount
that this variable is always defined. It should be set to the
mount point chosen for the LFS partition. Check that the
LFS variable is set up properly with:

echo $LFS

Make sure the output shows the path to the LFS partition's
mount point, which is /mnt/lfs if the
provided example was followed. If the output is incorrect, the
variable can be set with:

export LFS=/mnt/lfs

Having this variable set is beneficial in that commands such as
mkdir $LFS/tools
can be typed literally. The shell will automatically replace
“$LFS” with
“/mnt/lfs” (or whatever
the variable was set to) when it processes the command line.

Do not forget to check that $LFS is set
whenever you leave and reenter the current working environment
(as when doing a “su” to
root or another user).

4.2. Creating the
$LFS/tools Directory

All programs compiled in Chapter 5 will be installed
under $LFS/tools to keep them
separate from the programs compiled in Chapter 6. The programs compiled
here are temporary tools and will not be a part of the final
LFS system. By keeping these programs in a separate directory,
they can easily be discarded later after their use. This also
prevents these programs from ending up in the host production
directories (easy to do by accident in Chapter 5).

Create the required directory by running the following as
root:

mkdir -v $LFS/tools

The next step is to create a /tools
symlink on the host system. This will point to the
newly-created directory on the LFS partition. Run this command
as root as well:

ln -sv $LFS/tools /

Note

The above command is correct. The ln command has a few syntactic
variations, so be sure to check info coreutils ln and ln(1) before reporting what you may think
is an error.

The created symlink enables the toolchain to be compiled so
that it always refers to /tools,
meaning that the compiler, assembler, and linker will work both
in this chapter (when we are still using some tools from the
host) and in the next (when we are “chrooted” to the LFS partition).

4.3. Adding the LFS User

When logged in as user root, making a single mistake can
damage or destroy a system. Therefore, we recommend building
the packages in this chapter as an unprivileged user. You could
use your own user name, but to make it easier to set up a clean
working environment, create a new user called lfs as a member of a new group (also
named lfs) and use this
user during the installation process. As root, issue the following commands
to add the new user:

groupadd lfs
useradd -s /bin/bash -g lfs -m -k /dev/null lfs

The meaning of the command line options:

-s
/bin/bash

This makes bash the default shell for user
lfs.

-g
lfs

This option adds user lfs to group lfs.

-m

This creates a home directory for lfs.

-k
/dev/null

This parameter prevents possible copying of files from a
skeleton directory (default is /etc/skel) by changing the input location
to the special null device.

lfs

This is the actual name for the created group and user.

To log in as lfs (as
opposed to switching to user lfs when logged in as root, which does not require the
lfs user to have a
password), give lfs a
password:

passwd lfs

Grant lfs full access to
$LFS/tools by making lfs the directory owner:

chown -v lfs $LFS/tools

If a separate working directory was created as suggested, give
user lfs ownership of
this directory:

chown -v lfs $LFS/sources

Next, login as user lfs.
This can be done via a virtual console, through a display
manager, or with the following substitute user command:

su - lfs

The “-” instructs
su to start a
login shell as opposed to a non-login shell. The difference
between these two types of shells can be found in detail in
bash(1) and info bash.

4.4. Setting Up the
Environment

Set up a good working environment by creating two new startup
files for the bash shell. While logged in as user
lfs, issue the following
command to create a new .bash_profile:

When logged on as user lfs, the initial shell is usually a
login shell which reads
the /etc/profile of the host
(probably containing some settings and environment variables)
and then .bash_profile. The
exec env
-i.../bin/bash command in the .bash_profile file replaces the running shell
with a new one with a completely empty environment, except for
the HOME, TERM,
and PS1 variables. This ensures that no
unwanted and potentially hazardous environment variables from
the host system leak into the build environment. The technique
used here achieves the goal of ensuring a clean environment.

The new instance of the shell is a non-login shell, which does not read
the /etc/profile or .bash_profile files, but rather reads the
.bashrc file instead. Create the
.bashrc file now:

The set +h
command turns off bash's hash function. Hashing is
ordinarily a useful feature—bash uses a hash table to remember
the full path of executable files to avoid searching the
PATH time and again to find the same
executable. However, the new tools should be used as soon as
they are installed. By switching off the hash function, the
shell will always search the PATH when a
program is to be run. As such, the shell will find the newly
compiled tools in $LFS/tools as soon
as they are available without remembering a previous version of
the same program in a different location.

Setting the user file-creation mask (umask) to 022 ensures that
newly created files and directories are only writable by their
owner, but are readable and executable by anyone (assuming
default modes are used by the open(2) system call, new files
will end up with permission mode 644 and directories with mode
755).

The LFS variable should be set to the
chosen mount point.

The LC_ALL variable controls the
localization of certain programs, making their messages follow
the conventions of a specified country. If the host system uses
a version of Glibc older than 2.2.4, having LC_ALL set to something other than
“POSIX” or
“C” (during this
chapter) may cause issues if you exit the chroot environment
and wish to return later. Setting LC_ALL
to “POSIX” or
“C” (the two are
equivalent) ensures that everything will work as expected in
the chroot environment.

By putting /tools/bin ahead of the
standard PATH, all the programs
installed in Chapter 5
are picked up by the shell immediately after their
installation. This, combined with turning off hashing, limits
the risk that old programs are used from the host when the same
programs are available in the chapter 5 environment.

Finally, to have the environment fully prepared for building
the temporary tools, source the just-created user profile:

source ~/.bash_profile

4.5. About SBUs

Many people would like to know beforehand approximately how
long it takes to compile and install each package. Because
Linux From Scratch can be built on many different systems, it
is impossible to provide accurate time estimates. The biggest
package (Glibc) will take approximately 20 minutes on the
fastest systems, but could take up to three days on slower
systems! Instead of providing actual times, the Standard Build
Unit (SBU) measure will be used instead.

The SBU measure works as follows. The first package to be
compiled from this book is Binutils in Chapter 5. The time it takes to
compile this package is what will be referred to as the
Standard Build Unit or SBU. All other compile times will be
expressed relative to this time.

For example, consider a package whose compilation time is 4.5
SBUs. This means that if a system took 10 minutes to compile
and install the first pass of Binutils, it will take
approximately 45 minutes
to build this example package. Fortunately, most build times
are shorter than the one for Binutils.

In general, SBUs are not entirely accurate because they depend
on many factors, including the host system's version of GCC.
Note that on Symmetric Multi-Processor (SMP)-based machines,
SBUs are even less accurate. They are provided here to give an
estimate of how long it might take to install a package, but
the numbers can vary by as much as dozens of minutes in some
cases.

4.6. About the Test
Suites

Most packages provide a test suite. Running the test suite for
a newly built package is a good idea because it can provide a
“sanity check”
indicating that everything compiled correctly. A test suite
that passes its set of checks usually proves that the package
is functioning as the developer intended. It does not, however,
guarantee that the package is totally bug free.

Some test suites are more important than others. For example,
the test suites for the core toolchain packages—GCC,
Binutils, and Glibc—are of the utmost importance due to
their central role in a properly functioning system. The test
suites for GCC and Glibc can take a very long time to complete,
especially on slower hardware, but are strongly recommended.

Note

Experience has shown that there is little to be gained from
running the test suites in Chapter 5. There can be no
escaping the fact that the host system always exerts some
influence on the tests in that chapter, often causing
inexplicable failures. Because the tools built in Chapter 5 are temporary and
eventually discarded, we do not recommend running the test
suites in Chapter 5
for the average reader. The instructions for running those
test suites are provided for the benefit of testers and
developers, but they are strictly optional.

A common issue with running the test suites for Binutils and
GCC is running out of pseudo terminals (PTYs). This can result
in a high number of failing tests. This may happen for several
reasons, but the most likely cause is that the host system does
not have the devpts file system set
up correctly. This issue is discussed in greater detail in
Chapter 5.

Sometimes package test suites will fail, but for reasons which
the developers are aware of and have deemed non-critical.
Consult the logs located at http://www.linuxfromscratch.org/lfs/build-logs/6.1.1/
to verify whether or not these failures are expected. This site
is valid for all tests throughout this book.

Chapter 5. Constructing
a Temporary System

5.1. Introduction

This chapter shows how to compile and install a minimal Linux
system. This system will contain just enough tools to start
constructing the final LFS system in Chapter 6 and allow a working
environment with more user convenience than a minimum
environment would.

There are two steps in building this minimal system. The first
step is to build a new and host-independent toolchain
(compiler, assembler, linker, libraries, and a few useful
utilities). The second step uses this toolchain to build the
other essential tools.

The files compiled in this chapter will be installed under the
$LFS/tools directory to keep them
separate from the files installed in the next chapter and the
host production directories. Since the packages compiled here
are temporary, we do not want them to pollute the soon-to-be
LFS system.

Important

Before issuing the build instructions for a package, the
package should be unpacked as user lfs, and a cd into the created directory
should be performed. The build instructions assume that the
bash shell is
in use.

Several of the packages are patched before compilation, but
only when the patch is needed to circumvent a problem. A patch
is often needed in both this and the next chapter, but
sometimes in only one or the other. Therefore, do not be
concerned if instructions for a downloaded patch seem to be
missing. Warning messages about offset or fuzz may also be encountered when
applying a patch. Do not worry about these warnings, as the
patch was still successfully applied.

During the compilation of most packages, there will be several
warnings that scroll by on the screen. These are normal and can
safely be ignored. These warnings are as they
appear—warnings about deprecated, but not invalid, use of
the C or C++ syntax. C standards change fairly often, and some
packages still use the older standard. This is not a problem,
but does prompt the warning.

Important

After installing each package, delete its source and build
directories, unless specifically instructed otherwise.
Deleting the sources prevents mis-configuration when the
same package is reinstalled later. Only three of the
packages need to retain the source and build directories in
order for their contents to be used by later commands. Pay
special attention to these reminders.

Check one last time that the LFS
environment variable is set up properly:

echo $LFS

Make sure the output shows the path to the LFS partition's
mount point, which is /mnt/lfs, using
our example.

5.2. Toolchain
Technical Notes

This section explains some of the rationale and technical
details behind the overall build method. It is not essential to
immediately understand everything in this section. Most of this
information will be clearer after performing an actual build.
This section can be referred back to at any time during the
process.

The overall goal of Chapter
5 is to provide a temporary environment that can be
chrooted into and from which can be produced a clean,
trouble-free build of the target LFS system in Chapter 6. Along the way, we
separate the new system from the host system as much as
possible, and in doing so, build a self-contained and
self-hosted toolchain. It should be noted that the build
process has been designed to minimize the risks for new readers
and provide maximum educational value at the same time.

Important

Before continuing, be aware of the name of the working
platform, often referred to as the target triplet. Many
times, the target triplet will probably be i686-pc-linux-gnu. A simple way
to determine the name of the target triplet is to run the
config.guess
script that comes with the source for many packages. Unpack
the Binutils sources and run the script: ./config.guess and note the
output.

Also be aware of the name of the platform's dynamic linker,
often referred to as the dynamic loader (not to be confused
with the standard linker ld that is part of Binutils). The
dynamic linker provided by Glibc finds and loads the shared
libraries needed by a program, prepares the program to run,
and then runs it. The name of the dynamic linker will
usually be ld-linux.so.2. On
platforms that are less prevalent, the name might be
ld.so.1, and newer 64 bit
platforms might be named something else entirely. The name
of the platform's dynamic linker can be determined by
looking in the /lib directory on
the host system. A sure-fire way to determine the name is
to inspect a random binary from the host system by running:
readelf -l <name of
binary> | grep interpreter and noting the
output. The authoritative reference covering all platforms
is in the shlib-versions file in
the root of the Glibc source tree.

Careful manipulation of gcc's specs file tells the compiler which
target dynamic linker will be used

Binutils is installed first because the configure runs of both GCC and Glibc
perform various feature tests on the assembler and linker to
determine which software features to enable or disable. This is
more important than one might first realize. An incorrectly
configured GCC or Glibc can result in a subtly broken
toolchain, where the impact of such breakage might not show up
until near the end of the build of an entire distribution. A
test suite failure will usually highlight this error before too
much additional work is performed.

Binutils installs its assembler and linker in two locations,
/tools/bin and /tools/$TARGET_TRIPLET/bin. The tools in one
location are hard linked to the other. An important facet of
the linker is its library search order. Detailed information
can be obtained from ld by passing it the --verbose flag. For example, an
ld --verbose | grep
SEARCH will illustrate the current search paths
and their order. It shows which files are linked by
ld by compiling a
dummy program and passing the --verbose switch to the linker. For
example, gcc dummy.c
-Wl,--verbose 2>&1 | grep succeeded will
show all the files successfully opened during the linking.

The next package installed is GCC. An example of what can be
seen during its run of configure is:

checking what assembler to use...
/tools/i686-pc-linux-gnu/bin/as
checking what linker to use... /tools/i686-pc-linux-gnu/bin/ld

This is important for the reasons mentioned above. It also
demonstrates that GCC's configure script does not search the
PATH directories to find which tools to use. However, during
the actual operation of gcc itself, the same search paths are
not necessarily used. To find out which standard linker
gcc will use,
run: gcc
-print-prog-name=ld.

Detailed information can be obtained from gcc by passing it the -v command line option while
compiling a dummy program. For example, gcc -v dummy.c will show detailed
information about the preprocessor, compilation, and assembly
stages, including gcc's included search paths and their
order.

The next package installed is Glibc. The most important
considerations for building Glibc are the compiler, binary
tools, and kernel headers. The compiler is generally not an
issue since Glibc will always use the gcc found in a PATH directory. The binary tools and kernel
headers can be a bit more complicated. Therefore, take no risks
and use the available configure switches to enforce the correct
selections. After the run of configure, check the contents of the
config.make file in the glibc-build directory for all important
details. Note the use of CC="gcc
-B/tools/bin/" to control which binary tools are used
and the use of the -nostdinc and -isystem flags to control the
compiler's include search path. These items highlight an
important aspect of the Glibc package—it is very
self-sufficient in terms of its build machinery and generally
does not rely on toolchain defaults.

After the Glibc installation, make some adjustments to ensure
that searching and linking take place only within the
/tools prefix. Install an adjusted
ld, which has a
hard-wired search path limited to /tools/lib. Then amend gcc's specs file to point to the new
dynamic linker in /tools/lib. This
last step is vital to the whole process. As mentioned above, a
hard-wired path to a dynamic linker is embedded into every
Executable and Link Format (ELF)-shared executable. This can be
inspected by running: readelf -l
<name of binary> | grep interpreter.
Amending gcc's specs file ensures that every program compiled
from here through the end of this chapter will use the new
dynamic linker in /tools/lib.

The need to use the new dynamic linker is also the reason why
the Specs patch is applied for the second pass of GCC. Failure
to do so will result in the GCC programs themselves having the
name of the dynamic linker from the host system's /lib directory embedded into them, which would
defeat the goal of getting away from the host.

During the second pass of Binutils, we are able to utilize the
--with-lib-path configure
switch to control ld's library search path. From this
point onwards, the core toolchain is self-contained and
self-hosted. The remainder of the Chapter 5 packages all build
against the new Glibc in /tools.

Upon entering the chroot environment in Chapter 6, the first major
package to be installed is Glibc, due to its self-sufficient
nature mentioned above. Once this Glibc is installed into
/usr, perform a quick changeover of
the toolchain defaults, then proceed in building the rest of
the target LFS system.

5.3. Binutils-2.15.94.0.2.2
- Pass 1

The Binutils package contains a linker, an assembler, and
other tools for handling object files.

5.3.1. Installation of Binutils

It is important that Binutils be the first package compiled
because both Glibc and GCC perform various tests on the
available linker and assembler to determine which of their
own features to enable.

This package is known to have issues when its default
optimization flags (including the -march and -mcpu options) are changed. If any
environment variables that override default optimizations
have been defined, such as CFLAGS and
CXXFLAGS, unset them when building
Binutils.

If you are building from a host running Gcc-4 or later, it is
necessary to patch the first build of this version of
Binutils so that it can be compiled by the host system.

patch -Np1 -i ../binutils-2.15.94.0.2.2-gcc4-1.patch

The Binutils documentation recommends building Binutils
outside of the source directory in a dedicated build
directory:

mkdir -v ../binutils-build
cd ../binutils-build

Note

In order for the SBU values listed in the rest of the
book to be of any use, measure the time it takes to build
this package from the configuration, up to and including
the first install. To achieve this easily, wrap the three
commands in a time command like this:
time { ./configure ...
&& make && make install; }.

Now prepare Binutils for compilation:

../binutils-2.15.94.0.2.2/configure --prefix=/tools --disable-nls

The meaning of the configure options:

--prefix=/tools

This tells the configure script to prepare to install
the Binutils programs in the /tools directory.

--disable-nls

This disables internationalization as i18n is not
needed for the temporary tools.

Continue with compiling the package:

make

Compilation is now complete. Ordinarily we would now run the
test suite, but at this early stage the test suite framework
(Tcl, Expect, and DejaGNU) is not yet in place. The benefits
of running the tests at this point are minimal since the
programs from this first pass will soon be replaced by those
from the second.

Install the package:

make install

Next, prepare the linker for the “Adjusting” phase later on:

make -C ld clean
make -C ld LIB_PATH=/tools/lib

The meaning of the make parameters:

-C ld
clean

This tells the make program to remove all compiled
files in the ld subdirectory.

-C ld
LIB_PATH=/tools/lib

This option rebuilds everything in the ld subdirectory. Specifying the
LIB_PATH Makefile variable on
the command line allows us to override the default
value and point it to the temporary tools location. The
value of this variable specifies the linker's default
library search path. This preparation is used later in
the chapter.

Warning

Do not remove the
Binutils build and source directories yet. These will be
needed again in their current state later in this
chapter.

5.4.1. Installation of GCC

This package is known to have issues when its default
optimization flags (including the -march and -mcpu options) are changed. If any
environment variables that override default optimizations
have been defined, such as CFLAGS and
CXXFLAGS, unset them when building
GCC.

The GCC documentation recommends building GCC outside of the
source directory in a dedicated build directory:

The purpose of this switch is to remove /usr/local/include from
gcc's
include search path. This is not absolutely essential,
however, it helps to minimize the influence of the host
system.

--enable-shared

This switch allows the building of libgcc_s.so.1 and libgcc_eh.a. Having libgcc_eh.a available ensures that the
configure script for Glibc (the next package we
compile) produces the proper results.

--enable-languages=c

This option ensures that only the C compiler is built.

Continue with compiling the package:

make bootstrap

The meaning of the make parameters:

bootstrap

This target does not just compile GCC, but compiles it
several times. It uses the programs compiled in a first
round to compile itself a second time, and then again a
third time. It then compares these second and third
compiles to make sure it can reproduce itself
flawlessly. This also implies that it was compiled
correctly.

Compilation is now complete. At this point, the test suite
would normally be run, but, as mentioned before, the test
suite framework is not in place yet. The benefits of running
the tests at this point are minimal since the programs from
this first pass will soon be replaced.

Install the package:

make install

As a finishing touch, create a symlink. Many programs and
scripts run cc
instead of gcc,
which is used to keep programs generic and therefore usable
on all kinds of UNIX systems where the GNU C compiler is not
always installed. Running cc leaves the system administrator
free to decide which C compiler to install.

5.5. Linux-Libc-Headers-2.6.11.2

5.5.1. Installation of Linux-Libc-Headers

For years it has been common practice to use
“raw” kernel headers
(straight from a kernel tarball) in /usr/include, but over the last few years,
the kernel developers have taken a strong stance that this
should not be done. This gave birth to the Linux-Libc-Headers
Project, which was designed to maintain an Application
Programming Interface (API) stable version of the Linux
headers.

5.6.1. Installation of Glibc

This package is known to have issues when its default
optimization flags (including the -march and -mcpu options) are changed. If any
environment variables that override default optimizations
have been defined, such as CFLAGS and
CXXFLAGS, unset them when building
Glibc.

It should be noted that compiling Glibc in any way other than
the method suggested in this book puts the stability of the
system at risk.

Glibc has two tests which fail when the running kernel is
2.6.11 or later. The problem has been determined to be with
the tests themselves, not with the C library or the kernel.
If you plan to run the testsuite apply this patch:

patch -Np1 -i ../glibc-2.3.4-fix_test-1.patch

The Glibc documentation recommends building Glibc outside of
the source directory in a dedicated build directory:

This builds the libraries without profiling
information. Omit this option if profiling on the
temporary tools is necessary.

--enable-add-ons

This tells Glibc to use the NPTL add-on as its
threading library.

--enable-kernel=2.6.0

This tells Glibc to compile the library with support
for 2.6.x Linux kernels.

--with-binutils=/tools/bin

While not required, this switch ensures that there are
no errors pertaining to which Binutils programs get
used during the Glibc build.

--without-gd

This prevents the build of the memusagestat program, which
insists on linking against the host's libraries (libgd,
libpng, libz, etc.).

--with-headers=/tools/include

This tells Glibc to compile itself against the headers
recently installed to the tools directory, so that it
knows exactly what features the kernel has and can
optimize itself accordingly.

--without-selinux

When building from hosts that include SELinux
functionality (e.g. Fedora Core 3), Glibc will build
with support for SELinux. As the LFS tools environment
does not contain support for SELinux, a Glibc compiled
with such support will fail to operate correctly.

During this stage the following warning might appear:

configure: WARNING:
*** These auxiliary programs are missing or
*** incompatible versions: msgfmt
*** some features will be disabled.
*** Check the INSTALL file for required versions.

The missing or incompatible msgfmt program is generally
harmless, but it can sometimes cause issues when running the
test suite. This msgfmt program is part of the
Gettext package which the host distribution should provide.
If msgfmt is
present but deemed incompatible, upgrade the host system's
Gettext package or continue without it and see if the test
suite runs without problems regardless.

Compile the package:

make

Compilation is now complete. As mentioned earlier, running
the test suites for the temporary tools installed in this
chapter is not mandatory. To run the Glibc test suite (if
desired), the following command will do so:

In this chapter, some tests can be adversely affected by
existing tools or environmental issues on the host system.
Glibc test suite failures in this chapter are typically not
worrisome. The Glibc installed in Chapter 6 is the one that will
ultimately end up being used, so that is the one that needs
to pass most tests (even in Chapter 6, some failures could
still occur, for example, with the math tests).

When experiencing a failure, make a note of it, then continue
by reissuing the make
check command. The test suite should pick up
where it left off and continue. This stop-start sequence can
be circumvented by issuing a make -k check command. If using
this option, be sure to log the output so that the log file
can be examined for failures later.

The install stage of Glibc will issue a harmless warning at
the end about the absence of /tools/etc/ld.so.conf. Prevent this warning
with:

mkdir -v /tools/etc
touch /tools/etc/ld.so.conf

Install the package:

make install

Different countries and cultures have varying conventions for
how to communicate. These conventions range from the format
for representing dates and times to more complex issues, such
as the language spoken. The “internationalization” of GNU programs
works by locale.

Note

If the test suites are not being run in this chapter (as
per the recommendation), there is no need to install the
locales now. The appropriate locales will be installed in
the next chapter.

To install the Glibc locales anyway, use the following
command:

make localedata/install-locales

To save time, an alternative to running the previous command
(which generates and installs every locale Glibc is aware of)
is to install only those locales that are wanted and needed.
This can be achieved by using the localedef command. Information on
this command is located in the INSTALL file in the Glibc source. However,
there are a number of locales that are essential in order for
the tests of future packages to pass, in particular, the
libstdc++ tests from
GCC. The following instructions, instead of the install-locales target used above,
will install the minimum set of locales necessary for the
tests to run successfully:

5.7. Adjusting the
Toolchain

Now that the temporary C libraries have been installed, all
tools compiled in the rest of this chapter should be linked
against these libraries. In order to accomplish this, the
linker and the compiler's specs file need to be adjusted.

The linker, adjusted at the end of the first pass of Binutils,
is installed by running the following command from within the
binutils-build directory:

make -C ld install

From this point onwards, everything will link only against the
libraries in /tools/lib.

Note

If the earlier warning to retain the Binutils source and
build directories from the first pass was missed, ignore
the above command. This results in a small chance that the
subsequent testing programs will link against libraries on
the host. This is not ideal, but it is not a major problem.
The situation is corrected when the second pass of Binutils
is installed later.

Now that the adjusted linker is installed, the Binutils build
and source directories should be removed.

The next task is to amend the GCC specs file so that it points
to the new dynamic linker. A simple sed script will accomplish
this:

It is recommended that the above command be
copy-and-pasted in order to ensure accuracy.
Alternatively, the specs file can be edited by hand. This is
done by replacing every occurrence of “/lib/ld-linux.so.2” with
“/tools/lib/ld-linux.so.2”

Be sure to visually inspect the specs file in order to verify
the intended changes have been made.

Important

If working on a platform where the name of the dynamic
linker is something other than ld-linux.so.2, replace “ld-linux.so.2” with the name of the
platform's dynamic linker in the above commands. Refer back
to Section 5.2,
“Toolchain Technical Notes,” if necessary.

There is a possibility that some include files from the host
system have found their way into GCC's private include dir.
This can happen as a result of GCC's “fixincludes” process, which runs as part
of the GCC build. This is explained in more detail later in
this chapter. Run the following command to eliminate this
possibility:

rm -vf /tools/lib/gcc/*/*/include/{pthread.h,bits/sigthread.h}

Caution

At this point, it is imperative to stop and ensure that the
basic functions (compiling and linking) of the new
toolchain are working as expected. To perform a sanity
check, run the following commands:

If everything is working correctly, there should be no
errors, and the output of the last command will be of the
form:

[Requesting program interpreter:
/tools/lib/ld-linux.so.2]

Note that /tools/lib appears as
the prefix of the dynamic linker.

If the output is not shown as above or there was no output
at all, then something is wrong. Investigate and retrace
the steps to find out where the problem is and correct it.
This issue must be resolved before continuing on. First,
perform the sanity check again, using gcc instead of
cc. If this
works, then the /tools/bin/cc
symlink is missing. Revisit Section 5.4,
“GCC-3.4.3 - Pass 1,” and install the
symlink. Next, ensure that the PATH
is correct. This can be checked by running
echo $PATH
and verifying that /tools/bin is
at the head of the list. If the PATH
is wrong it could mean that you are not logged in as user
lfs or that
something went wrong back in Section 4.4,
“Setting Up the Environment.” Another
option is that something may have gone wrong with the specs
file amendment above. In this case, redo the specs file
amendment, being careful to copy-and-paste the
commands.

Once all is well, clean up the test files:

rm -v dummy.c a.out

Building TCL in the next section will serve as an
additional check that the toolchain has been built
properly. If TCL fails to build, it is an indication that
something has gone wrong with the Binutils, GCC, or Glibc
installation, but not with TCL itself.

5.8.1. Installation of Tcl

This package and the next two (Expect and DejaGNU) are
installed to support running the test suites for GCC and
Binutils. Installing three packages for testing purposes may
seem excessive, but it is very reassuring, if not essential,
to know that the most important tools are working properly.
Even if the test suites are not run in this chapter (they are
not mandatory), these packages are required to run the test
suites in Chapter 6.

Prepare Tcl for compilation:

cd unix
./configure --prefix=/tools

Build the package:

make

To test the results, issue: TZ=UTC make test. The Tcl test
suite is known to experience failures under certain host
conditions that are not fully understood. Therefore, test
suite failures here are not surprising, and are not
considered critical. The TZ=UTC parameter sets the time zone
to Coordinated Universal Time (UTC), also known as Greenwich
Mean Time (GMT), but only for the duration of the test suite
run. This ensures that the clock tests are exercised
correctly. Details on the TZ
environment variable are provided in Chapter 7.

Install the package:

make install

Warning

Do not remove the
tcl8.4.9 source directory yet,
as the next package will need its internal headers.

Set a variable containing the full path of the current
directory. The next package, Expect, will use this variable
to find Tcl's headers.

cd ..
export TCLPATH=`pwd`

Now make a necessary symbolic link:

ln -sv tclsh8.4 /tools/bin/tclsh

5.8.2. Contents of Tcl

Installed
programs:tclsh (link
to tclsh8.4) and tclsh8.4

Installed
library:libtcl8.4.so

Short Descriptions

tclsh8.4

The Tcl command shell

tclsh

A link to tclsh8.4

libtcl8.4.so

The Tcl library

5.9. Expect-5.43.0

The Expect package contains a program for carrying out
scripted dialogues with other interactive programs.

This ensures that the configure script finds the Tcl
installation in the temporary tools location instead of
possibly locating an existing one on the host system.

--with-tclinclude=$TCLPATH

This explicitly tells Expect where to find Tcl's source
directory and internal headers. Using this option
avoids conditions where configure fails because it
cannot automatically discover the location of the Tcl
source directory.

--with-x=no

This tells the configure script not to search for Tk
(the Tcl GUI component) or the X Window System
libraries, both of which may reside on the host system
but will not exist in the temporary environment.

Build the package:

make

To test the results, issue: make test. Note that the Expect
test suite is known to experience failures under certain host
conditions that are not within our control. Therefore, test
suite failures here are not surprising and are not considered
critical.

Install the package:

make SCRIPTS="" install

The meaning of the make parameter:

SCRIPTS=""

This prevents installation of the supplementary expect
scripts, which are not needed.

Now remove the TCLPATH variable:

unset TCLPATH

The source directories of both Tcl and Expect can now be
removed.

5.9.2. Contents of Expect

Installed
program:expect

Installed
library:libexpect-5.43.a

Short Descriptions

expect

Communicates with other interactive programs
according to a script

libexpect-5.43.a

Contains functions that allow Expect to be used as
a Tcl extension or to be used directly from C or
C++ (without Tcl)

5.11. GCC-3.4.3 - Pass 2

5.11.1. Re-installation of GCC

This package is known to have issues when its default
optimization flags (including the -march and -mcpu options) are changed. If any
environment variables that override default optimizations
have been defined, such as CFLAGS and
CXXFLAGS, unset them when building
GCC.

The tools required to test GCC and Binutils—Tcl, Expect
and DejaGNU—are installed now. GCC and Binutils can now
be rebuilt, linking them against the new Glibc and testing
them properly (if running the test suites in this chapter).
Please note that these test suites are highly dependent on
properly functioning PTYs which are provided by the host.
PTYs are most commonly implemented via the devpts file system. Check to see if the
host system is set up correctly in this regard by performing
a quick test:

expect -c "spawn ls"

The response might be:

The system has no more ptys.
Ask your system administrator to create more.

If the above message is received, the host does not have its
PTYs set up properly. In this case, there is no point in
running the test suites for GCC and Binutils until this issue
is resolved. Please consult the LFS FAQ at http://www.linuxfromscratch.org//lfs/faq.html#no-ptys
for more information on how to get PTYs working.

The first patch disables the GCC fixincludes script. This was
briefly mentioned earlier, but a more in-depth explanation of
the fixincludes process is warranted here. Under normal
circumstances, the GCC fixincludes script scans the system
for header files that need to be fixed. It might find that
some Glibc header files on the host system need to be fixed,
and will fix them and put them in the GCC private include
directory. In Chapter
6, after the newer Glibc has been installed, this private
include directory will be searched before the system include
directory. This may result in GCC finding the fixed headers
from the host system, which most likely will not match the
Glibc version used for the LFS system.

The second patch changes GCC's default location of the
dynamic linker (typically ld-linux.so.2). It also removes /usr/include from GCC's include search path.
Patching now rather than adjusting the specs file after
installation ensures that the new dynamic linker is used
during the actual build of GCC. That is, all of the final
(and temporary) binaries created during the build will link
against the new Glibc.

Important

The above patches are critical in ensuring a successful
overall build. Do not forget to apply them.

Create a separate build directory again:

mkdir -v ../gcc-build
cd ../gcc-build

Before starting to build GCC, remember to unset any
environment variables that override the default optimization
flags.

This option ensures the correct locale model is
selected for the C++ libraries under all circumstances.
If the configure script finds the de_DE locale installed, it
will select the correct gnu locale model. However, if
the de_DE locale
is not installed, there is the risk of building
Application Binary Interface (ABI)-incompatible C++
libraries because the incorrect generic locale model
may be selected.

--enable-threads=posix

This enables C++ exception handling for multi-threaded
code.

--enable-__cxa_atexit

This option allows use of __cxa_atexit, rather than
atexit, to
register C++ destructors for local statics and global
objects. This option is essential for fully
standards-compliant handling of destructors. It also
affects the C++ ABI, and therefore results in C++
shared libraries and C++ programs that are
interoperable with other Linux distributions.

--enable-languages=c,c++

This option ensures that both the C and C++ compilers
are built.

--disable-libstdcxx-pch

Do not build the pre-compiled header (PCH) for
libstdc++. It takes up a lot
of space, and we have no use for it.

Compile the package:

make

There is no need to use the bootstrap target now because the
compiler being used to compile this GCC was built from the
exact same version of the GCC sources used earlier.

Compilation is now complete. As previously mentioned, running
the test suites for the temporary tools compiled in this
chapter is not mandatory. To run the GCC test suite anyway,
use the following command:

make -k check

The -k flag is used to
make the test suite run through to completion and not stop at
the first failure. The GCC test suite is very comprehensive
and is almost guaranteed to generate a few failures. To
receive a summary of the test suite results, run:

A few unexpected failures cannot always be avoided. The GCC
developers are usually aware of these issues, but have not
resolved them yet. Unless the test results are vastly
different from those at the above URL, it is safe to
continue.

Install the package:

make install

Note

At this point it is strongly recommended to repeat the
sanity check we performed earlier in this chapter. Refer
back to Section 5.7,
“Adjusting the Toolchain,” and repeat the
test compilation. If the result is wrong, the most likely
reason is that the GCC Specs patch was not properly
applied.

5.12.1. Re-installation of Binutils

This package is known to have issues when its default
optimization flags (including the -march and -mcpu options) are changed. If any
environment variables that override default optimizations
have been defined, such as CFLAGS and
CXXFLAGS, unset them when building
Binutils.

This tells the configure script to specify the library
search path during the compilation of Binutils,
resulting in /tools/lib being
passed to the linker. This prevents the linker from
searching through library directories on the host.

Compile the package:

make

Compilation is now complete. As discussed earlier, running
the test suite is not mandatory for the temporary tools here
in this chapter. To run the Binutils test suite anyway, issue
the following command:

make check

Install the package:

make install

Now prepare the linker for the “Re-adjusting” phase in the next chapter:

make -C ld clean
make -C ld LIB_PATH=/usr/lib:/lib

Warning

Do not remove the
Binutils source and build directories yet. These
directories will be needed again in the next chapter in
their current state.

5.14.1. Installation of Coreutils

Prepare Coreutils for compilation:

DEFAULT_POSIX2_VERSION=199209 ./configure --prefix=/tools

This package has an issue when compiled against versions of
Glibc later than 2.3.2. Some of the Coreutils utilities (such
as head,
tail, and
sort) will
reject their traditional syntax, a syntax that has been in
use for approximately 30 years. This old syntax is so
pervasive that compatibility should be preserved until the
many places where it is used can be updated. Backwards
compatibility is achieved by setting the DEFAULT_POSIX2_VERSION environment variable to
“199209” in the above
command. If you do not want Coreutils to be backwards
compatible with the traditional syntax, then omit setting the
DEFAULT_POSIX2_VERSION environment
variable. It is important to remember that doing so will have
consequences, including the need to patch the many packages
that still use the old syntax. Therefore, it is recommended
that the instructions be followed exactly as given above.

Compile the package:

make

To test the results, issue: make RUN_EXPENSIVE_TESTS=yes
check. The RUN_EXPENSIVE_TESTS=yes parameter
tells the test suite to run several additional tests that are
considered relatively expensive (in terms of CPU power and
memory usage) on some platforms, but generally are not a
problem on Linux.

5.18. Findutils-4.2.23

The Findutils package contains programs to find files. These
programs are provided to recursively search through a
directory tree and to create, maintain, and search a database
(often faster than the recursive find, but unreliable if the
database has not been recently updated).

5.20.1. Installation of Grep

Prepare Grep for compilation:

./configure --prefix=/tools \
--disable-perl-regexp

The meaning of the configure options:

--disable-perl-regexp

This ensures that the grep program does not get
linked against a Perl Compatible Regular Expression
(PCRE) library that may be present on the host but will
not be available once we enter the chroot environment.

5.22. Gettext-0.14.3

The Gettext package contains utilities for
internationalization and localization. These allow programs
to be compiled with NLS (Native Language Support), enabling
them to output messages in the user's native language.

5.22.1. Installation of Gettext

This flag tells Gettext not to build the asprintf library. Because nothing in
this chapter or the next requires this library and
Gettext gets rebuilt later, exclude it to save time and
space.

--without-csharp

This ensures that Gettext does not build support for
the C# compiler which may be present on the host but
will not be available once we enter the
chroot
environment.

Compile the package:

make

To test the results, issue: make check. This takes quite
some time, around 7 SBUs. The Gettext test suite is known to
experience failures under certain host conditions, for
example when it finds a Java compiler on the host. An
experimental patch to disable Java is available from the LFS
Patches project at http://www.linuxfromscratch.org/patches/.

5.27.1. Installation of Bash

Bash has a problem when compiled against newer versions of
Glibc, causing it to hang inappropriately. This patch fixes
the problem:

patch -Np1 -i ../bash-3.0-avoid_WCONTINUED-1.patch

Prepare Bash for compilation:

./configure --prefix=/tools --without-bash-malloc

The meaning of the configure options:

--without-bash-malloc

This options turns off the use of Bash's memory
allocation (malloc) function which is known to cause
segmentation faults. By turning this option off, Bash
will use the malloc functions from Glibc which are more
stable.

5.30.1. Installation of Flex

Flex contains several known bugs. These can be fixed with the
following patch:

patch -Np1 -i ../flex-2.5.31-debian_fixes-3.patch

The GNU autotools will detect that the Flex source code has
been modified by the previous patch and tries to update the
man page accordingly. This does not work on many systems, and
the default page is fine, so make sure it does not get
regenerated:

5.32.1. Installation of Perl

First adapt some hard-wired paths to the C library by
applying the following patch:

patch -Np1 -i ../perl-5.8.7-libc-1.patch

Prepare Perl for compilation (make sure to get the 'IO Fcntl
POSIX' part of the command correct—they are all
letters):

./configure.gnu --prefix=/tools -Dstatic_ext='IO Fcntl POSIX'

The meaning of the configure options:

-Dstatic_ext='IO Fcntl
POSIX'

This tells Perl to build the minimum set of static
extensions needed for installing and testing the
Coreutils package in the next chapter.

Only a few of the utilities contained in this package need to
be built:

make perl utilities

Although Perl comes with a test suite, it is not recommended
to run it at this point. Only part of Perl was built and
running make test
now will cause the rest of Perl to be built as well, which is
unnecessary at this point. The test suite can be run in the
next chapter if desired.

5.33. Stripping

The steps in this section are optional, but if the LFS
partition is rather small, it is beneficial to learn that
unnecessary items can be removed. The executables and libraries
built so far contain about 130 MB of unneeded debugging
symbols. Remove those symbols with:

The last of the above commands will skip some twenty files,
reporting that it does not recognize their file format. Most of
these are scripts instead of binaries.

Take care not to use
--strip-unneeded on the
libraries. The static ones would be destroyed and the toolchain
packages would need to be built all over again.

To save another 30 MB, remove the documentation:

rm -rf /tools/{info,man}

There will now be at least 850 MB of free space on the LFS file
system that can be used to build and install Glibc in the next
phase. If you can build and install Glibc, you can build and
install the rest too.

8. Making the LFS System Bootable

9. The End

Chapter 6. Installing
Basic System Software

6.1. Introduction

In this chapter, we enter the building site and start
constructing the LFS system in earnest. That is, we chroot into
the temporary mini Linux system, make a few final preparations,
and then begin installing the packages.

The installation of this software is straightforward. Although
in many cases the installation instructions could be made
shorter and more generic, we have opted to provide the full
instructions for every package to minimize the possibilities
for mistakes. The key to learning what makes a Linux system
work is to know what each package is used for and why the user
(or the system) needs it. For every installed package, a
summary of its contents is given, followed by concise
descriptions of each program and library the package installed.

If using the compiler optimizations provided in this chapter,
please review the optimization hint at http://www.linuxfromscratch.org/hints/downloads/files/optimization.txt.
Compiler optimizations can make a program run slightly faster,
but they may also cause compilation difficulties and problems
when running the program. If a package refuses to compile when
using optimization, try to compile it without optimization and
see if that fixes the problem. Even if the package does compile
when using optimization, there is the risk it may have been
compiled incorrectly because of the complex interactions
between the code and build tools. The small potential gains
achieved in using compiler optimizations are often outweighed
by the risks. First-time builders of LFS are encouraged to
build without custom optimizations. The subsequent system will
still run very fast and be stable at the same time.

The order that packages are installed in this chapter needs to
be strictly followed to ensure that no program accidentally
acquires a path referring to /tools
hard-wired into it. For the same reason, do not compile
packages in parallel. Compiling in parallel may save time
(especially on dual-CPU machines), but it could result in a
program containing a hard-wired path to /tools, which will cause the program to stop
working when that directory is removed.

Before the installation instructions, each installation page
provides information about the package, including a concise
description of what it contains, approximately how long it will
take to build, how much disk space is required during this
building process, and any other packages needed to successfully
build the package. Following the installation instructions,
there is a list of programs and libraries (along with brief
descriptions of these) that the package installs.

Note

The remainder of this book is to be performed while logged
in as user root and
no longer as user lfs. Also, double check that
$LFS is set.

6.2. Mounting Virtual Kernel
File Systems

Various file systems exported by the kernel are used to
communicate to and from the kernel itself. These file systems
are virtual in that no disk space is used for them. The content
of the file systems resides in memory.

Begin by creating directories onto which the file systems will
be mounted:

mkdir -pv $LFS/{proc,sys}

Now mount the file systems:

mount -vt proc proc $LFS/proc
mount -vt sysfs sysfs $LFS/sys

Remember that if for any reason you stop working on the LFS
system and start again later, it is important to check that
these file systems are mounted again before entering the chroot
environment.

Additional file systems will soon be mounted from within the
chroot environment. To keep the host up to date, perform a
“fake mount” for each of
these now:

6.3. Entering the Chroot
Environment

It is time to enter the chroot environment to begin building
and installing the final LFS system. As user root, run the following command to
enter the realm that is, at the moment, populated with only the
temporary tools:

The -i option given to the
env command will
clear all variables of the chroot environment. After that, only
the HOME, TERM,
PS1, and PATH
variables are set again. The TERM=$TERM construct will set the
TERM variable inside chroot to the same
value as outside chroot. This variable is needed for programs
like vim and
less to operate
properly. If other variables are needed, such as CFLAGS or CXXFLAGS, this is
a good place to set them again.

From this point on, there is no need to use the LFS variable anymore, because all work will be
restricted to the LFS file system. This is because the Bash
shell is told that $LFS is now the
root (/) directory.

Notice that /tools/bin comes last in
the PATH. This means that a temporary
tool will no longer be used once its final version is
installed. This occurs when the shell does not
“remember” the locations
of executed binaries—for this reason, hashing is switched
off by passing the +h
option to bash.

It is important that all the commands throughout the remainder
of this chapter and the following chapters are run from within
the chroot environment. If you leave this environment for any
reason (rebooting for example), remember to first mount the
proc and devpts file systems (discussed in the
previous section) and enter chroot again before continuing with
the installations.

Note that the bash prompt will say I have no name! This is normal because
the /etc/passwd file has not been
created yet.

6.4. Changing
Ownership

Currently, the /tools directory is
owned by the user lfs, a
user that exists only on the host system. Although the
/tools directory can be deleted once
the LFS system has been finished, it can be retained to build
additional LFS systems. If the /tools
directory is kept as is, the files are owned by a user ID
without a corresponding account. This is dangerous because a
user account created later could get this same user ID and
would own the /tools directory and
all the files therein, thus exposing these files to possible
malicious manipulation.

To avoid this issue, add the lfs user to the new LFS system later
when creating the /etc/passwd file,
taking care to assign it the same user and group IDs as on the
host system. Alternatively, assign the contents of the
/tools directory to user root by running the following
command:

chown -R 0:0 /tools

The command uses 0:0
instead of root:root,
because chown is
unable to resolve the name “root” until the password file has been
created. This book assumes you ran this chown command.

6.5. Creating
Directories

It is time to create some structure in the LFS file system.
Create a standard directory tree by issuing the following
commands:

Directories are, by default, created with permission mode 755,
but this is not desirable for all directories. In the commands
above, two changes are made—one to the home directory of
user root, and another
to the directories for temporary files.

The first mode change ensures that not just anybody can enter
the /root directory—the same as
a normal user would do with his or her home directory. The
second mode change makes sure that any user can write to the
/tmp and /var/tmp directories, but cannot remove another
user's files from them. The latter is prohibited by the
so-called “sticky bit,”
the highest bit (1) in the 1777 bit mask.

6.5.1. FHS Compliance Note

The directory tree is based on the Filesystem Hierarchy
Standard (FHS) (available at http://www.pathname.com/fhs/).
In addition to the tree created above, this standard
stipulates the existence of /usr/local/games and /usr/share/games. The FHS is not precise as
to the structure of the /usr/local/share subdirectory, so we create
only the directories that are needed. However, feel free to
create these directories if you prefer to conform more
strictly to the FHS.

6.6. Creating Essential
Symlinks

Some programs use hard-wired paths to programs which do not
exist yet. In order to satisfy these programs, create a number
of symbolic links which will be replaced by real files
throughout the course of this chapter after the software has
been installed.

The created groups are not part of any standard—they are
groups decided on in part by the requirements of the Udev
configuration in this chapter, and in part by common convention
employed by a number of existing Linux distributions. The Linux
Standard Base (LSB, available at http://www.linuxbase.org)
recommends only that, besides the group “root” with a Group ID (GID) of 0, a group
“bin” with a GID of 1 be
present. All other group names and GIDs can be chosen freely by
the system administrator since well-written programs do not
depend on GID numbers, but rather use the group's name.

To remove the “I have no
name!” prompt, start a new shell. Since a full
Glibc was installed in Chapter 5 and the /etc/passwd and /etc/group files have been created, user name
and group name resolution will now work.

exec /tools/bin/bash --login +h

Note the use of the +h
directive. This tells bash not to use its internal path
hashing. Without this directive, bash would remember the paths to
binaries it has executed. To ensure the use of the newly
compiled binaries as soon as they are installed, the +h directive will be used for the
duration of this chapter.

The login,
agetty, and
init programs
(and others) use a number of log files to record information
such as who was logged into the system and when. However, these
programs will not write to the log files if they do not already
exist. Initialize the log files and give them proper
permissions:

The /var/run/utmp file records the
users that are currently logged in. The /var/log/wtmp file records all logins and
logouts. The /var/log/lastlog file
records when each user last logged in. The /var/log/btmp file records the bad login
attempts.

6.8. Populating /dev

6.8.1. Creating Initial Device Nodes

When the kernel boots the system, it requires the presence of
a few device nodes, in particular the console and null
devices. The device nodes will be created on the hard disk so
that they are available before udev has been started, and
additionally when Linux is started in single user mode (hence
the restrictive permissions on console). Create the devices by running the
following commands:

mknod -m 600 /dev/console c 5 1
mknod -m 666 /dev/null c 1 3

6.8.2. Mounting tmpfs and Populating /dev

The recommended method of populating the /dev directory with devices is to mount a
virtual filesystem (such as tmpfs) on the /dev directory, and allow the devices to be
created dynamically on that virtual filesystem as they are
detected or accessed. This is generally done during the boot
process. Since this new system has not been booted, it is
necessary to do what the LFS-Bootscripts package would
otherwise do by mounting /dev:

mount -nvt tmpfs none /dev

The Udev package is what actually creates the devices in the
/dev directory. Since it will not
be installed until later on in the process, manually create
the minimal set of device nodes needed to complete the
building of this system:

There are some symlinks and directories required by LFS that
are created during system startup by the LFS-Bootscripts
package. Since this is a chroot environment and not a booted
environment, those symlinks and directories need to be
created here:

6.9. Linux-Libc-Headers-2.6.11.2

6.9.1. Installation of Linux-Libc-Headers

For years it has been common practice to use
“raw” kernel headers
(straight from a kernel tarball) in /usr/include, but over the last few years,
the kernel developers have taken a strong stance that this
should not be done. This gave birth to the Linux-Libc-Headers
Project, which was designed to maintain an API stable version
of the Linux headers.

6.11.1. Installation of Glibc

Note

Some packages outside of LFS suggest installing GNU
libiconv in order to translate data from one encoding to
another. The project's home page (http://www.gnu.org/software/libiconv/)
says “This library provides an
iconv() implementation, for use
on systems which don't have one, or whose implementation
cannot convert from/to Unicode. ” Glibc
provides an iconv()
implementation and can convert from/to Unicode, therefore
libiconv is not required on an LFS system.

This package is known to have issues when its default
optimization flags (including the -march and -mcpu options) are changed. If any
environment variables that override default optimizations
have been defined, such as CFLAGS and
CXXFLAGS, unset them when building
Glibc.

The Glibc build system is self-contained and will install
perfectly, even though the compiler specs file and linker are
still pointing at /tools. The specs
and linker cannot be adjusted before the Glibc install
because the Glibc autoconf tests would give false results and
defeat the goal of achieving a clean build.

The linuxthreads tarball contains the man pages for the
threading libraries installed by Glibc. Unpack the tarball
from within the Glibc source directory:

tar -xjvf ../glibc-linuxthreads-2.3.4.tar.bz2

In certain rare circumstances, Glibc can segfault when no
standard search directories exist. The following patch
prevents this:

patch -Np1 -i ../glibc-2.3.4-rtld_search_dirs-1.patch

Glibc has two tests which fail when the running kernel is
2.6.11.x The problem has been determined to be with the tests
themselves, not with the libc nor the kernel. This patch
fixes the problem:

patch -Np1 -i ../glibc-2.3.4-fix_test-1.patch

Apply the following patch to fix a bug in Glibc that can
prevent some programs (including OpenOffice.org) from
running:

patch -Np1 -i ../glibc-2.3.4-tls_assert-1.patch

The Glibc documentation recommends building Glibc outside of
the source directory in a dedicated build directory:

This changes the location of the pt_chown program from its
default of /usr/libexec to
/usr/lib/glibc.

Compile the package:

make

Important

In this section, the test suite for Glibc is considered
critical. Do not skip it under any circumstance.

Test the results:

make -k check >glibc-check-log 2>&1
grep Error glibc-check-log

The Glibc test suite is highly dependent on certain functions
of the host system, in particular the kernel. In general, the
Glibc test suite is always expected to pass. However, in
certain circumstances, some failures are unavoidable. This is
a list of the most common issues:

The math tests
sometimes fail when running on systems where the CPU is
not a relatively new genuine Intel or authentic AMD.
Certain optimization settings are also known to be a
factor here.

The gettext test
sometimes fails due to host system issues. The exact
reasons are not yet clear.

When running on older and slower hardware, some tests
can fail because of test timeouts being exceeded.

Though it is a harmless message, the install stage of Glibc
will complain about the absence of /etc/ld.so.conf. Prevent this warning with:

touch /etc/ld.so.conf

Install the package:

make install

The locales that can make the system respond in a different
language were not installed by the above command. Install
this with:

make localedata/install-locales

To save time, an alternative to running the previous command
(which generates and installs every locale listed in the
glibc-2.3.4/localedata/SUPPORTED file) is to install only
those locales that are wanted and needed. This can be
achieved by using the localedef command. Information on
this command is located in the INSTALL file in the Glibc source. However,
there are a number of locales that are essential in order for
the tests of future packages to pass, in particular, the
libstdc++ tests from
GCC. The following instructions, instead of the install-locales target used above,
will install the minimum set of locales necessary for the
tests to run successfully:

Some locales installed by the make localedata/install-locales
command above are not properly supported by some applications
that are in the LFS and BLFS books. Because of the various
problems that arise due to application programmers making
assumptions that break in such locales, LFS should not be
used in locales that utilize multibyte character sets
(including UTF-8) or right-to-left writing order. Numerous
unofficial and unstable patches are required to fix these
problems, and it has been decided by the LFS developers not
to support such complex locales at this time. This applies to
the ja_JP and fa_IR locales as well—they have been
installed only for GCC and Gettext tests to pass, and the
watch program
(part of the Procps package) does not work properly in them.
Various attempts to circumvent these restrictions are
documented in internationalization-related hints.

Build the linuxthreads man pages, which are a great reference
on the threading API (applicable to NPTL as well):

make -C ../glibc-2.3.4/linuxthreads/man

Install these pages:

make -C ../glibc-2.3.4/linuxthreads/man install

6.11.2. Configuring Glibc

The /etc/nsswitch.conf file needs
to be created because, although Glibc provides defaults when
this file is missing or corrupt, the Glibc defaults do not
work well in a networked environment. The time zone also
needs to be configured.

After answering a few questions about the location, the
script will output the name of the time zone (e.g.,
EST5EDT or
Canada/Eastern). Then
create the /etc/localtime file by
running:

cp -v --remove-destination /usr/share/zoneinfo/[xxx] \
/etc/localtime

Replace [xxx] with the
name of the time zone that tzselect provided (e.g.,
Canada/Eastern).

The meaning of the cp option:

--remove-destination

This is needed to force removal of the already existing
symbolic link. The reason for copying the file instead
of using a symlink is to cover the situation where
/usr is on a separate
partition. This could be important when booted into
single user mode.

6.11.3. Configuring Dynamic Loader

By default, the dynamic loader (/lib/ld-linux.so.2) searches through
/lib and /usr/lib for dynamic libraries that are
needed by programs as they are run. However, if there are
libraries in directories other than /lib and /usr/lib,
these need to be added to the /etc/ld.so.conf file in order for the dynamic
loader to find them. Two directories that are commonly known
to contain additional libraries are /usr/local/lib and /opt/lib, so add those directories to the
dynamic loader's search path.

Contains profiling functions used to track the
amount of CPU time spent in specific source code
lines

libpthread

The POSIX threads library

libresolv

Contains functions for creating, sending, and
interpreting packets to the Internet domain name
servers

librpcsvc

Contains functions providing miscellaneous RPC
services

librt

Contains functions providing most of the interfaces
specified by the POSIX.1b Realtime Extension

libthread_db

Contains functions useful for building debuggers
for multi-threaded programs

libutil

Contains code for “standard” functions used in
many different Unix utilities

6.12. Re-adjusting the
Toolchain

Now that the final C libraries have been installed, it is time
to adjust the toolchain again. The toolchain will be adjusted
so that it will link any newly compiled program against these
new libraries. This is the same process used in the
“Adjusting” phase in the
beginning of Chapter 5,
but with the adjustments reversed. In Chapter 5, the chain was guided
from the host's /{,usr/}lib
directories to the new /tools/lib
directory. Now, the chain will be guided from that same
/tools/lib directory to the LFS
/{,usr/}lib directories.

Start by adjusting the linker. The source and build directories
from the second pass of Binutils were retained for this
purpose. Install the adjusted linker by running the following
command from within the binutils-build directory:

make -C ld INSTALL=/tools/bin/install install

Note

If the earlier warning to retain the Binutils source and
build directories from the second pass in Chapter 5 was missed, or if
they were accidentally deleted or are inaccessible, ignore
the above command. The result will be that the next
package, Binutils, will link against the C libraries in
/tools rather than in /{,usr/}lib. This is not ideal, however,
testing has shown that the resulting Binutils program
binaries should be identical.

From now on, every compiled program will link only against the
libraries in /usr/lib and /lib. The extra INSTALL=/tools/bin/install option is
needed because the Makefile file
created during the second pass still contains the reference to
/usr/bin/install,
which has not been installed yet. Some host distributions
contain a ginstall symbolic link
which takes precedence in the Makefile file and can cause a problem. The
above command takes care of this issue.

Remove the Binutils source and build directories now.

Next, amend the GCC specs file so that it points to the new
dynamic linker. A perl command accomplishes this:

It is a good idea to visually inspect the specs file to verify
the intended change was actually made.

Important

If working on a platform where the name of the dynamic
linker is something other than ld-linux.so.2, substitute
“ld-linux.so.2” with
the name of the platform's dynamic linker in the above
commands. Refer back to Section 5.2,
“Toolchain Technical Notes,” if necessary.

Caution

It is imperative at this point to stop and ensure that the
basic functions (compiling and linking) of the adjusted
toolchain are working as expected. To do this, perform a
sanity check:

echo 'main(){}' > dummy.c
cc dummy.c
readelf -l a.out | grep ': /lib'

If everything is working correctly, there should be no
errors, and the output of the last command will be
(allowing for platform-specific differences in dynamic
linker name):

[Requesting program interpreter: /lib/ld-linux.so.2]

Note that /lib is now the prefix
of our dynamic linker.

If the output does not appear as shown above or is not
received at all, then something is seriously wrong.
Investigate and retrace the steps to find out where the
problem is and correct it. The most likely reason is that
something went wrong with the specs file amendment above.
Any issues will need to be resolved before continuing on
with the process.

Once everything is working correctly, clean up the test
files:

rm -v dummy.c a.out

6.13. Binutils-2.15.94.0.2.2

The Binutils package contains a linker, an assembler, and
other tools for handling object files.

6.13.1. Installation of Binutils

This package is known to have issues when its default
optimization flags (including the -march and -mcpu options) are changed. If any
environment variables that override default optimizations
have been defined, such as CFLAGS and
CXXFLAGS, unset them when building
Binutils.

Verify that the PTYs are working properly inside the chroot
environment. Check that everything is set up correctly by
performing a simple test:

expect -c "spawn ls"

If the following message shows up, the chroot environment is
not set up for proper PTY operation:

The system has no more ptys.
Ask your system administrator to create more.

This issue needs to be resolved before running the test
suites for Binutils and GCC.

The Binutils documentation recommends building Binutils
outside of the source directory in a dedicated build
directory:

mkdir -v ../binutils-build
cd ../binutils-build

Prepare Binutils for compilation:

../binutils-2.15.94.0.2.2/configure --prefix=/usr \
--enable-shared

Compile the package:

make tooldir=/usr

Normally, the tooldir (the directory where the executables
will ultimately be located) is set to $(exec_prefix)/$(target_alias). For example,
i686 machines would expand that to /usr/i686-pc-linux-gnu. Because this is a
custom system, this target-specific directory in /usr is not required. $(exec_prefix)/$(target_alias) would be used
if the system was used to cross-compile (for example,
compiling a package on an Intel machine that generates code
that can be executed on PowerPC machines).

Important

The test suite for Binutils in this section is considered
critical. Do not skip it under any circumstances.

6.13.2. Contents of Binutils

Short Descriptions

addr2line

Translates program addresses to file names and line
numbers; given an address and the name of an
executable, it uses the debugging information in
the executable to determine which source file and
line number are associated with the address

ar

Creates, modifies, and extracts from archives

as

An assembler that assembles the output of
gcc
into object files

c++filt

Used by the linker to de-mangle C++ and Java
symbols and to keep overloaded functions from
clashing

gprof

Displays call graph profile data

ld

A linker that combines a number of object and
archive files into a single file, relocating their
data and tying up symbol references

nm

Lists the symbols occurring in a given object file

objcopy

Translates one type of object file into another

objdump

Displays information about the given object file,
with options controlling the particular information
to display; the information shown is useful to
programmers who are working on the compilation
tools

ranlib

Generates an index of the contents of an archive
and stores it in the archive; the index lists all
of the symbols defined by archive members that are
relocatable object files

readelf

Displays information about ELF type binaries

size

Lists the section sizes and the total size for the
given object files

strings

Outputs, for each given file, the sequences of
printable characters that are of at least the
specified length (defaulting to four); for object
files, it prints, by default, only the strings from
the initializing and loading sections while for
other types of files, it scans the entire file

strip

Discards symbols from object files

libiberty

Contains routines used by various GNU programs,
including getopt,
obstack,
strerror,
strtol, and
strtoul

libbfd

The Binary File Descriptor library

libopcodes

A library for dealing with opcodes—the
“readable
text” versions of instructions for the
processor; it is used for building utilities like
objdump.

6.14. GCC-3.4.3

The GCC package contains the GNU compiler collection, which
includes the C and C++ compilers.

6.14.1. Installation of GCC

This package is known to have issues when its default
optimization flags (including the -march and -mcpu options) are changed. If any
environment variables that override default optimizations
have been defined, such as CFLAGS and
CXXFLAGS, unset them when building
GCC.

Apply only the No-Fixincludes patch (not the Specs patch)
also used in the previous chapter:

patch -Np1 -i ../gcc-3.4.3-no_fixincludes-1.patch

GCC fails to compile some packages outside of a base Linux
From Scratch install (e.g., Mozilla and kdegraphics) when
used in conjunction with newer versions of Binutils. Apply
the following patch to fix this issue:

patch -Np1 -i ../gcc-3.4.3-linkonce-1.patch

Apply a sed
substitution that will suppress the installation of
libiberty.a. The version of
libiberty.a provided by Binutils
will be used instead:

sed -i 's/install_to_$(INSTALL_DEST) //' libiberty/Makefile.in

The GCC documentation recommends building GCC outside of the
source directory in a dedicated build directory:

Important

In this section, the test suite for GCC is considered
critical. Do not skip it under any circumstance.

Test the results, but do not stop at errors:

make -k check

Some of the errors are known issues and were noted in the
previous chapter. The test suite notes from Section 5.11,
“GCC-3.4.3 - Pass 2,” are still relevant
here. Be sure to refer back to them as necessary.

Install the package:

make install

Some packages expect the C preprocessor to be installed in
the /lib directory. To support
those packages, create this symlink:

ln -sv ../usr/bin/cpp /lib

Many packages use the name cc to call the C compiler. To
satisfy those packages, create a symlink:

ln -sv gcc /usr/bin/cc

Note

At this point, it is strongly recommended to repeat the
sanity check performed earlier in this chapter. Refer
back to Section 6.12,
“Re-adjusting the Toolchain,” and repeat
the check. If the results are in error, then the most
likely reason is that the GCC Specs patch from Chapter 5 was erroneously
applied here.

6.15.1. Installation of Coreutils

A known issue with the uname program from this package is
that the -p switch always
returns unknown. The
following patch fixes this behavior for Intel architectures:

patch -Np1 -i ../coreutils-5.2.1-uname-2.patch

Prevent Coreutils from installing binaries that will be
installed by other packages later:

patch -Np1 -i ../coreutils-5.2.1-suppress_uptime_kill_su-1.patch

Now prepare Coreutils for compilation:

DEFAULT_POSIX2_VERSION=199209 ./configure --prefix=/usr

Compile the package:

make

The test suite of Coreutils makes several assumptions about
the presence of system users and groups that are not valid
within the minimal environment that exists at the moment.
Therefore, additional items need to be set up before running
the tests. Skip down to “Install
the package” if not running the test suite.

6.16.1. Installation of Zlib

Note

Zlib is known to build its shared library incorrectly if
CFLAGS is specified in the
environment. If using a specified CFLAGS variable, be sure to add the
-fPIC directive to
the CFLAGS variable for the
duration of the configure command below, then remove it
afterwards.

Prepare Zlib for compilation:

./configure --prefix=/usr --shared --libdir=/lib

Compile the package:

make

To test the results, issue: make check.

Install the shared library:

make install

The previous command installed a .so file in /lib.
We will remove it and relink it into /usr/lib:

rm -v /lib/libz.so
ln -sfv ../../lib/libz.so.1.2.3 /usr/lib/libz.so

Build the static library:

make clean
./configure --prefix=/usr
make

To test the results again, issue: make check.

Install the static library:

make install

Fix the permissions on the static library:

chmod -v 644 /usr/lib/libz.a

6.16.2. Contents of Zlib

Installed
libraries:libz.[a,so]

Short Descriptions

libz

Contains compression and decompression functions
used by some programs

6.17.1. Installation of Mktemp

Many scripts still use the deprecated tempfile program, which has
functionality similar to mktemp. Patch Mktemp to include a
tempfile
wrapper:

patch -Np1 -i ../mktemp-1.5-add_tempfile-2.patch

Prepare Mktemp for compilation:

./configure --prefix=/usr --with-libc

The meaning of the configure options:

--with-libc

This causes the mktemp program to use the
mkstemp and
mkdtemp
functions from the system C library.

Compile the package:

make

Install the package:

make install
make install-tempfile

6.17.2. Contents of Mktemp

Installed
programs:mktemp and
tempfile

Short Descriptions

mktemp

Creates temporary files in a secure manner; it is
used in scripts

tempfile

Creates temporary files in a less secure manner
than mktemp; it is installed
for backwards-compatibility

6.18. Iana-Etc-1.04

The Iana-Etc package provides data for network services and
protocols.

Approximate build
time:0.1 SBU

Required disk
space:1.9 MB

Installation depends
on:Make

6.18.1. Installation of Iana-Etc

The following command converts the raw data provided by IANA
into the correct formats for the /etc/protocols and /etc/services data files:

make

Install the package:

make install

6.18.2. Contents of Iana-Etc

Installed
files:/etc/protocols
and /etc/services

Short Descriptions

/etc/protocols

Describes the various DARPA Internet protocols that
are available from the TCP/IP subsystem

/etc/services

Provides a mapping between friendly textual names
for internet services, and their underlying
assigned port numbers and protocol types

6.19. Findutils-4.2.23

The Findutils package contains programs to find files. These
programs are provided to recursively search through a
directory tree and to create, maintain, and search a database
(often faster than the recursive find, but unreliable if the
database has not been recently updated).

The terminfo action checker; it is mainly used to
test the accuracy of an entry in the terminfo
database

tic

The terminfo entry-description compiler that
translates a terminfo file from source format into
the binary format needed for the ncurses library
routines. A terminfo file contains information on
the capabilities of a certain terminal

toe

Lists all available terminal types, giving the
primary name and description for each

tput

Makes the values of terminal-dependent capabilities
available to the shell; it can also be used to
reset or initialize a terminal or report its long
name

tset

Can be used to initialize terminals

libcurses

A link to libncurses

libncurses

Contains functions to display text in many complex
ways on a terminal screen; a good example of the
use of these functions is the menu displayed during
the kernel's make
menuconfig

libform

Contains functions to implement forms

libmenu

Contains functions to implement menus

libpanel

Contains functions to implement panels

6.22. Readline-5.0

The Readline package is a set of libraries that offers
command-line editing and history capabilities.

6.22.1. Installation of Readline

The following patch includes a fix for a problem where
Readline sometimes only shows 33 characters on a line and
then wraps to the next line. It also includes other fixes
recommended by the Readline author.

6.23.1. Installation of Vim

First, unpack both vim-6.3.tar.bz2
and (optionally) vim-6.3-lang.tar.gz archives into the same
directory. Then, change the default location of the
vimrc configuration file to
/etc:

echo '#define SYS_VIMRC_FILE "/etc/vimrc"' >> src/feature.h

Vim has two known security vulnerabilities that have already
been addressed upstream. The following patch fixes the
problems:

patch -Np1 -i ../vim-6.3-security_fix-2.patch

Now prepare Vim for compilation:

./configure --prefix=/usr --enable-multibyte

The meaning of the configure options:

--enable-multibyte

This optional but highly recommended switch enables
support for editing files in multibyte character
encodings. This is needed if using a locale with a
multibyte character set. This switch is also helpful to
be able to edit text files initially created in Linux
distributions like Fedora Core that use UTF-8 as a
default character set.

Compile the package:

make

To test the results, issue: make test. However, this test
suite outputs a lot of binary data to the screen, which can
cause issues with the settings of the current terminal. This
can be resolved by redirecting the output to a log file.

Install the package:

make install

Many users are used to using vi instead of vim. To allow execution of
vim when users
habitually enter vi, create a symlink:

ln -sv vim /usr/bin/vi

If an X Window System is going to be installed on the LFS
system, it may be necessary to recompile Vim after installing
X. Vim comes with a GUI version of the editor that requires X
and some additional libraries to be installed. For more
information on this process, refer to the Vim documentation
and the Vim installation page in the BLFS book at http://www.linuxfromscratch.org/blfs/view/svn/postlfs/editors.html#postlfs-editors-vim.

6.23.2. Configuring Vim

By default, vim
runs in vi-incompatible mode. This may be new to users who
have used other editors in the past. The “nocompatible” setting is included below
to highlight the fact that a new behavior is being used. It
also reminds those who would change to “compatible” mode that it should be the
first setting in the configuration file. This is necessary
because it changes other settings, and overrides must come
after this setting. Create a default vim configuration file by running
the following:

The set nocompatible
makes vim
behave in a more useful way (the default) than the
vi-compatible manner. Remove the “no” to keep the old vi behavior. The set backspace=2 allows backspacing
over line breaks, autoindents, and the start of insert. The
syntax on enables vim's
syntax highlighting. Finally, the if statement with the set background=dark corrects
vim's guess
about the background color of some terminal emulators. This
gives the highlighting a better color scheme for use on the
black background of these programs.

Documentation for other available options can be obtained by
running the following command:

6.24.1. Installation of M4

6.24.2. Contents of M4

Installed
program:m4

Short Descriptions

m4

copies the given files while expanding the macros
that they contain. These macros are either built-in
or user-defined and can take any number of
arguments. Besides performing macro expansion,
m4
has built-in functions for including named files,
running Unix commands, performing integer
arithmetic, manipulating text, recursion, etc. The
m4
program can be used either as a front-end to a
compiler or as a macro processor in its own right.

Short Descriptions

Reads a troff font file and adds some additional
font-metric information that is used by the
groff
system

afmtodit

Creates a font file for use with
groff
and grops

eqn

Compiles descriptions of equations embedded within
troff input files into commands that are understood
by troff

eqn2graph

Converts a troff EQN (equation) into a cropped
image

geqn

A link to eqn

grn

A groff preprocessor for
gremlin files

grodvi

A driver for groff that produces TeX
dvi format

groff

A front-end to the groff document formatting
system; normally, it runs the troff program and a
post-processor appropriate for the selected device

groffer

Displays groff files and man pages on X and tty
terminals

grog

Reads files and guesses which of the
groff
options -e,
-man,
-me, -mm, -ms, -p, -s, and -t are required for
printing files, and reports the
groff
command including those options

grolbp

Is a groff driver for Canon
CAPSL printers (LBP-4 and LBP-8 series laser
printers)

grolj4

Is a driver for groff that produces
output in PCL5 format suitable for an HP LaserJet 4
printer

grops

Translates the output of GNU troff to PostScript

grotty

Translates the output of GNU troff into a form
suitable for typewriter-like devices

gtbl

A link to tbl

hpftodit

Creates a font file for use with
groff
-Tlj4 from an HP-tagged font metric
file

indxbib

Creates an inverted index for the bibliographic
databases with a specified file for use with
refer,
lookbib, and
lkbib

lkbib

Searches bibliographic databases for references
that contain specified keys and reports any
references found

lookbib

Prints a prompt on the standard error (unless the
standard input is not a terminal), reads a line
containing a set of keywords from the standard
input, searches the bibliographic databases in a
specified file for references containing those
keywords, prints any references found on the
standard output, and repeats this process until the
end of input

Compiles descriptions of pictures embedded within
troff or TeX input files into commands understood
by TeX or troff

pic2graph

Converts a PIC diagram into a cropped image

post-grohtml

Translates the output of GNU troff to HTML

pre-grohtml

Translates the output of GNU troff to HTML

refer

Copies the contents of a file to the standard
output, except that lines between .[ and .] are interpreted as
citations, and lines between .R1 and .R2 are interpreted as
commands for how citations are to be processed

soelim

Reads files and replaces lines of the form
.so file by
the contents of the mentioned file

tbl

Compiles descriptions of tables embedded within
troff input files into commands that are understood
by troff

tfmtodit

Creates a font file for use with
groff
-Tdvi

troff

Is highly compatible with Unix troff; it should usually
be invoked using the groff command, which will
also run preprocessors and post-processors in the
appropriate order and with the appropriate options

6.29.1. Installation of Flex

Flex contains several known bugs. Fix these with the
following patch:

patch -Np1 -i ../flex-2.5.31-debian_fixes-3.patch

The GNU autotools detects that the Flex source code has been
modified by the previous patch and tries to update the man
page accordingly. This does not work correctly on many
systems, and the default page is fine, so make sure it does
not get regenerated:

touch doc/flex.1

Prepare Flex for compilation:

./configure --prefix=/usr

Compile the package:

make

To test the results, issue: make check.

Install the package:

make install

There are some packages that expect to find the lex library in /usr/lib. Create a symlink to account for
this:

ln -sv libfl.a /usr/lib/libl.a

A few programs do not know about flex yet and try to run its
predecessor, lex. To support those programs,
create a wrapper script named lex
that calls flex in
lex emulation
mode:

6.29.2. Contents of Flex

Short Descriptions

A tool for generating programs that recognize
patterns in text; it allows for the versatility to
specify the rules for pattern-finding, eradicating
the need to develop a specialized program

lex

A script that runs flex in
lex
emulation mode

libfl.a

The flex library

6.30. Gettext-0.14.3

The Gettext package contains utilities for
internationalization and localization. These allow programs
to be compiled with NLS (Native Language Support), enabling
them to output messages in the user's native language.

This option prevents Inetutils from installing the
logger
program, which is used by scripts to pass messages to
the System Log Daemon. Do not install it because
Util-linux installs a better version later.

--disable-syslogd

This option prevents Inetutils from installing the
System Log Daemon, which is installed with the Sysklogd
package.

--disable-whois

This option disables the building of the Inetutils
whois
client, which is out of date. Instructions for a better
whois
client are in the BLFS book.

--disable-servers

This disables the installation of the various network
servers included as part of the Inetutils package.
These servers are deemed not appropriate in a basic LFS
system. Some are insecure by nature and are only
considered safe on trusted networks. More information
can be found at http://www.linuxfromscratch.org/blfs/view/svn/basicnet/inetutils.html.
Note that better replacements are available for many of
these servers.

6.32.1. Installation of IPRoute2

The arpd binary
included in this package is dependent on Berkeley DB. Because
arpd is not a
very common requirement on a base Linux system, remove the
dependency on Berkeley DB by applying the
sed command
below. If the arpd binary is needed, instructions
for compiling Berkeley DB can be found in the BLFS Book at
http://www.linuxfromscratch.org/blfs/view/svn/server/databases.html#db.

sed -i '/^TARGETS/s@arpd@@g' misc/Makefile

Prepare IPRoute2 for compilation:

./configure

Compile the package:

make SBINDIR=/sbin

The meaning of the make option:

SBINDIR=/sbin

This ensures that the IPRoute2 binaries will install
into /sbin. This is the
correct location according to the FHS, because some of
the IPRoute2 binaries are used by the LFS-Bootscripts
package.

6.33.1. Installation of Perl

To have full control over the way Perl is set up, run the
interactive Configure script and hand-pick the
way this package is built. If the defaults it auto-detects
are suitable, prepare Perl for compilation with:

./configure.gnu --prefix=/usr -Dpager="/bin/less -isR"

The meaning of the configure options:

-Dpager="/bin/less -isR"

This corrects an error in the way that
perldoc
invokes the less program.

Compile the package:

make

To run the test suite, first create a basic /etc/hosts file which is needed by a couple
of the tests to resolve the network name localhost:

6.34.1. Installation of Texinfo

Texinfo allows local users to overwrite arbitrary files via a
symlink attack on temporary files. Apply the following patch
to fix this:

patch -Np1 -i ../texinfo-4.8-tempfile_fix-1.patch

Prepare Texinfo for compilation:

./configure --prefix=/usr

Compile the package:

make

To test the results, issue: make check.

Install the package:

make install

Optionally, install the components belonging in a TeX
installation:

make TEXMF=/usr/share/texmf install-tex

The meaning of the make parameter:

TEXMF=/usr/share/texmf

The TEXMF makefile variable
holds the location of the root of the TeX tree if, for
example, a TeX package will be installed later.

The Info documentation system uses a plain text file to hold
its list of menu entries. The file is located at /usr/share/info/dir. Unfortunately, due to
occasional problems in the Makefiles of various packages, it
can sometimes get out of sync with the info pages installed
on the system. If the /usr/share/info/dir file ever needs to be
recreated, the following optional commands will accomplish
the task:

6.35.2. Contents of Autoconf

Short Descriptions

autoconf

Produces shell scripts that automatically configure
software source code packages to adapt to many
kinds of Unix-like systems. The configuration
scripts it produces are independent—running
them does not require the autoconf program.

autoheader

A tool for creating template files of C
#define
statements for configure to use

autom4te

A wrapper for the M4 macro processor

autoreconf

Automatically runs autoconf,
autoheader,
aclocal,
automake,
gettextize, and
libtoolize in the correct
order to save time when changes are made to
autoconf and
automake template files

autoscan

Helps to create a configure.in file for a software
package; it examines the source files in a
directory tree, searching them for common
portability issues, and creates a configure.scan file that serves as
as a preliminary configure.in file for the package

autoupdate

Modifies a configure.in
file that still calls autoconf macros by their
old names to use the current macro names

ifnames

Helps when writing configure.in files for a software
package; it prints the identifiers that the package
uses in C preprocessor conditionals. If a package
has already been set up to have some portability,
this program can help determine what
configure needs to check
for. It can also fill in gaps in a configure.in file generated by
autoscan

6.36. Automake-1.9.5

The Automake package contains programs for generating
Makefiles for use with Autoconf.

Short Descriptions

acinstall

A script that installs aclocal-style M4 files

aclocal

Generates aclocal.m4
files based on the contents of configure.in files

aclocal-1.9.5

A hard link to aclocal

automake

A tool for automatically generating Makefile.in files from Makefile.am files. To create all
the Makefile.in files for
a package, run this program in the top-level
directory. By scanning the configure.in file, it automatically
finds each appropriate Makefile.am file and generates the
corresponding Makefile.in
file

automake-1.9.5

A hard link to automake

compile

A wrapper for compilers

config.guess

A script that attempts to guess the canonical
triplet for the given build, host, or target
architecture

config.sub

A configuration validation subroutine script

depcomp

A script for compiling a program so that dependency
information is generated in addition to the desired
output

elisp-comp

Byte-compiles Emacs Lisp code

install-sh

A script that installs a program, script, or data
file

mdate-sh

A script that prints the modification time of a
file or directory

missing

A script acting as a common stub for missing GNU
programs during an installation

6.40.1. Installation of Bzip2

Apply a patch to install the documentation for this package:

patch -Np1 -i ../bzip2-1.0.3-install_docs-1.patch

The bzgrep
command does not escape '|' and '&' in filenames passed
to it. This allows arbitrary commands to be executed with the
privileges of the user running bzgrep. Apply the following to
address this:

patch -Np1 -i ../bzip2-1.0.3-bzgrep_security-1.patch

Prepare Bzip2 for compilation with:

make -f Makefile-libbz2_so
make clean

The -f flag will cause
Bzip2 to be built using a different Makefile file, in this case the Makefile-libbz2_so file, which creates a
dynamic libbz2.so library and links
the Bzip2 utilities against it.

Compile and test the package:

make

If reinstalling Bzip2, perform rm -vf /usr/bin/bz* first,
otherwise the following make
install will fail.

Install the programs:

make install

Install the shared bzip2 binary into the /bin directory, make some necessary symbolic
links, and clean up:

Compresses files using the Burrows-Wheeler block
sorting text compression algorithm with Huffman
coding; the compression rate is better than that
achieved by more conventional compressors using
“Lempel-Ziv”
algorithms, like gzip

Certain programs (such as the e2fsck program) are
considered essential programs. When, for example,
/usr is not mounted, these
programs still need to be available. They belong in
directories like /lib and
/sbin. If this option is not
passed to E2fsprogs' configure, the programs are
installed into the /usr
directory.

--enable-elf-shlibs

This creates the shared libraries which some programs
in this package use.

--disable-evms

This disables the building of the Enterprise Volume
Management System (EVMS) plugin. This plugin is not
up-to-date with the latest EVMS internal interfaces and
EVMS is not installed as part of a base LFS system, so
the plugin is not required. See the EVMS website at
http://evms.sourceforge.net/
for more information regarding EVMS.

6.45.1. Installation of GRUB

This package is known to have issues when its default
optimization flags (including the -march and -mcpu options) are changed. If any
environment variables that override default optimizations
have been defined, such as CFLAGS and
CXXFLAGS, unset them when building
GRUB.

Prepare GRUB for compilation:

./configure --prefix=/usr

Compile the package:

make

To test the results, issue: make check.

Note that the test results will always show the error
“ufs2_stage1_5 is too
big.” This is due to a compiler issue, but can
be ignored unless you plan to boot from an UFS partition. The
partitions are normally only used by Sun workstations.

Replace i386-pc with whatever
directory is appropriate for the hardware in use.

The i386-pc directory contains a
number of *stage1_5 files,
different ones for different file systems. Review the files
available and copy the appropriate ones to the /boot/grub directory. Most users will copy
the e2fs_stage1_5 and/or reiserfs_stage1_5 files.

6.46.1. Installation of Gzip

Gzip has 2 known security vulnerabilities. The following
patch addresses both of them:

patch -Np1 -i ../gzip-1.3.5-security_fixes-1.patch

Prepare Gzip for compilation:

./configure --prefix=/usr

The gzexe
script has the location of the gzip binary hard-wired into it.
Because the location of the binary is changed later, the
following command ensures that the new location gets placed
into the script:

sed -i 's@"BINDIR"@/bin@g' gzexe.in

Compile the package:

make

Install the package:

make install

Move the gzip
program to the /bin directory and
create some commonly used symlinks to it:

Forces a .gz extension on
all given files that are gzipped files, so that
gzip
will not compress them again; this can be useful
when file names were truncated during a file
transfer

zgrep

Runs grep on gzipped files

zless

Runs less on gzipped files

zmore

Runs more on gzipped files

znew

Re-compresses files from compress format to
gzip
format—.Z to
.gz

6.47. Hotplug-2004_09_23

The Hotplug package contains scripts that react upon hotplug
events generated by the kernel. Such events correspond to
every change in the kernel state visible in the sysfs filesystem, e.g., the addition and
removal of hardware. This package also detects existing
hardware during boot and inserts the relevant modules into
the running kernel.

Approximate build
time:0.01 SBU

Required disk
space:460 KB

Installation depends
on:Bash, Coreutils,
Find, Gawk, and Make

6.47.1. Installation of Hotplug

Install the Hotplug package:

make install

Copy a file that the “install” target omits.

cp -v etc/hotplug/pnp.distmap /etc/hotplug

Remove the init script that Hotplug installs since we are
going to be using the script included in the LFS-Bootscripts
package:

rm -rfv /etc/init.d

Network device hotplugging is not yet supported by the
LFS-Bootscripts package. For that reason, remove the network
hotplug agent:

rm -fv /etc/hotplug/net.agent

Create a directory for storing firmware that can be loaded by
hotplug:

Short Descriptions

hotplug

This script is called by default by the Linux
kernel when something changes in its internal state
(e.g., a new device is added or an existing device
is removed)

/etc/hotplug/*.rc

These scripts are used for cold plugging, i.e.,
detecting and acting upon hardware already present
during system startup. They are called by the
hotplug initscript
included in the LFS-Bootscripts package. The
*.rc
scripts try to recover hotplug events that were
lost during system boot because, for example, the
root filesystem was not mounted by the kernel

/etc/hotplug/*.agent

These scripts are called by hotplug in response to
different types of hotplug events generated by the
kernel. Their action is to insert corresponding
kernel modules and call any user-provided scripts

/etc/hotplug/blacklist

This file contains the list of modules that should
never be inserted into the kernel by the Hotplug
scripts

/etc/hotplug/hotplug.functions

This file contains common functions used by other
scripts in the Hotplug package

/etc/hotplug/{pci,usb}

These directories contain user-written handlers for
hotplug events

/etc/hotplug/usb.usermap

This file contains rules that determine which
user-defined handlers to call for each USB device,
based on its vendor ID and other attributes

/etc/hotplug.d

This directory contains programs (or symlinks to
them) that are interested in receiving hotplug
events. For example, Udev puts its symlink here
during installation

/lib/firmware

This directory contains the firmware for devices
that need to have their firmware loaded before use

/var/log/hotplug/events

This file contains all the events that
hotplug has called since
bootup

6.48.1. Installation of Man

The first is a sed substitution to add the
-R switch to the
PAGER variable so that escape
sequences are properly handled by Less:

sed -i 's@-is@&R@g' configure

The second is also a sed substitution to comment out the
“MANPATH /usr/man”
line in the man.conf file to
prevent redundant results when using programs such as
whatis:

sed -i 's@MANPATH./usr/man@#&@g' src/man.conf.in

Prepare Man for compilation:

./configure -confdir=/etc

The meaning of the configure options:

-confdir=/etc

This tells the man program to look for the
man.conf configuration file
in the /etc directory.

Compile the package:

make

Install the package:

make install

Note

If you will be working on a terminal that does not
support text attributes such as color and bold, you can
disable Select Graphic Rendition (SGR) escape sequences
by editing the man.conf file
and adding the -c
option to the NROFF variable. If
you use multiple terminal types for one computer it may
be better to selectively add the GROFF_NO_SGR environment variable for the
terminals that do not support SGR.

If the character set of the locale uses 8-bit characters,
search for the line beginning with “NROFF” in /etc/man.conf, and verify that it matches the
following:

NROFF /usr/bin/nroff -Tlatin1 -mandoc

Note that “latin1”
should be used even if it is not the character set of the
locale. The reason is that, according to the specification,
groff has no
means of typesetting characters outside International
Organization for Standards (ISO) 8859-1 without some strange
escape codes. When formatting man pages, groff thinks that they are in the
ISO 8859-1 encoding and this -Tlatin1 switch tells
groff to use
the same encoding for output. Since groff does no recoding of input
characters, the formatted result is really in the same
encoding as input, and therefore it is usable as the input
for a pager.

This does not solve the problem of a non-working
man2dvi program
for localized man pages in non-ISO 8859-1 locales. Also, it
does not work with multibyte character sets. The first
problem does not currently have a solution. The second issue
is not of concern because the LFS installation does not
support multibyte character sets.

6.50.1. Installation of Module-Init-Tools

Module-Init-Tools attempts to rewrite its modprobe.conf man page during the build
process. This is unnecessary and also relies on
docbook2man
— which is not installed in LFS. Run the following
command to avoid this:

touch modprobe.conf.5

If you wish to run the test suite for Module-Init-Tools, you
will need to download the separate testsuite tarball. Issue
the following commands to perform the tests (note that the
make distclean
command is required to clean up the source tree, as the
source gets recompiled as part of the testing process):

6.51.1. Installation of Patch

Prepare Patch for compilation. The preprocessor flag
-D_GNU_SOURCE is only
needed on the PowerPC platform. It can be left it out on
other architectures:

CPPFLAGS=-D_GNU_SOURCE ./configure --prefix=/usr

Compile the package:

make

This package does not come with a test suite.

Install the package:

make install

6.51.2. Contents of Patch

Installed
program:patch

Short Descriptions

patch

Modifies files according to a patch file. A patch
file is normally a difference listing created with
the diff program. By applying
these differences to the original files,
patch
creates the patched versions.

6.53.1. Installation of Psmisc

Prepare Psmisc for compilation:

./configure --prefix=/usr --exec-prefix=""

The meaning of the configure options:

--exec-prefix=""

This ensures that the Psmisc binaries will install into
/bin instead of /usr/bin. This is the correct location
according to the FHS, because some of the Psmisc
binaries are used by the LFS-Bootscripts package.

Compile the package:

make

Install the package:

make install

There is no reason for the pstree and pstree.x11 programs to reside in
/bin. Therefore, move them to
/usr/bin:

mv -v /bin/pstree* /usr/bin

By default, Psmisc's pidof program is not installed.
This usually is not a problem because it is installed later
in the Sysvinit package, which provides a better
pidof program.
If Sysvinit will not be used for a particular system,
complete the installation of Psmisc by creating the following
symlink:

Shadow uses two files to
configure authentication settings for the system. Install
these two configuration files:

cp -v etc/{limits,login.access} /etc

Instead of using the default
crypt method, use the
more secure MD5 method
of password encryption, which also allows passwords longer
than 8 characters. It is also necessary to change the
obsolete /var/spool/mail location
for user mailboxes that Shadow uses by default to the
/var/mail location used currently.
Both of these can be accomplished by changing the relevant
configuration file while copying it to its destination:

Note

If you built Shadow with Cracklib support, insert the
following into the sed given below:

The -D option of the
useradd program
requires the /etc/default directory
for it to work properly:

mkdir -v /etc/default

6.54.2. Configuring Shadow

This package contains utilities to add, modify, and delete
users and groups; set and change their passwords; and perform
other administrative tasks. For a full explanation of what
password shadowing
means, see the doc/HOWTO file
within the unpacked source tree. If using Shadow support,
keep in mind that programs which need to verify passwords
(display managers, FTP programs, pop3 daemons, etc.) must be
Shadow-compliant. That is, they need to be able to work with
shadowed passwords.

To enable shadowed passwords, run the following command:

pwconv

To enable shadowed group passwords, run:

grpconv

Under normal circumstances, passwords will not have been
created yet. However, if returning to this section later to
enable shadowing, reset any current user passwords with the
passwd command
or any group passwords with the gpasswd command.

6.55.3. Contents of Sysklogd

Installed
programs:klogd and
syslogd

Short Descriptions

klogd

A system daemon for intercepting and logging kernel
messages

syslogd

Logs the messages that system programs offer for
logging. Every logged message contains at least a
date stamp and a hostname, and normally the
program's name too, but that depends on how
trusting the logging daemon is told to be

6.56. Sysvinit-2.86

The Sysvinit package contains programs for controlling the
startup, running, and shutdown of the system.

Approximate build
time:0.1 SBU

Required disk
space:1012 KB

Installation depends
on:Binutils,
Coreutils, GCC, Glibc, and Make

6.56.1. Installation of Sysvinit

When run-levels are changed (for example, when halting the
system), init
sends termination signals to those processes that
init itself
started and that should not be running in the new run-level.
While doing this, init outputs messages like
“Sending processes the TERM
signal” which seem to imply that it is sending
these signals to all currently running processes. To avoid
this misinterpretation, modify the source so that these
messages read like “Sending
processes started by init the TERM signal”
instead:

The -I '\033(K' option
tells agetty to
send this escape sequence to the terminal before doing
anything else. This escape sequence switches the console
character set to a user-defined one, which can be modified by
running the setfont program. The
console
initscript from the LFS-Bootscripts package calls the
setfont program
during system startup. Sending this escape sequence is
necessary for people who use non-ISO 8859-1 screen fonts, but
it does not affect native English speakers.

Short Descriptions

A daemon that reorders hotplug events before
submitting them to udev, thus avoiding
various race conditions

udevsend

Delivers hotplug events to udevd

udevstart

Creates device nodes in /dev that correspond to drivers
compiled directly into the kernel; it performs that
task by simulating hotplug events presumably
dropped by the kernel before invocation of this
program (e.g., because the root filesystem has not
been mounted) and submitting such synthetic hotplug
events to udev

udevinfo

Allows users to query the udev database for
information on any device currently present on the
system; it also provides a way to query any device
in the sysfs tree to
help create udev rules

udevtest

Simulates a udev run for the given
device, and prints out the name of the node the
real udev would have created
or (not in LFS) the name of the renamed network
interface

Attaches the file system on the given device to a
specified directory in the file-system tree

namei

Shows the symbolic links in the given pathnames

pg

Displays a text file one screen full at a time

pivot_root

Makes the given file system the new root file
system of the current process

ramsize

Sets the size of the RAM disk in a bootable image

raw

Used to bind a Linux raw character device to a
block device

rdev

Queries and sets the root device, among other
things, in a bootable image

readprofile

Reads kernel profiling information

rename

Renames the given files, replacing a given string
with another

renice

Alters the priority of running processes

rev

Reverses the lines of a given file

rootflags

Sets the rootflags in a bootable image

script

Makes a typescript of a terminal session

setfdprm

Sets user-provided floppy disk parameters

setsid

Runs the given program in a new session

setterm

Sets terminal attributes

sfdisk

A disk partition table manipulator

swapdev

Sets the swap device in a bootable image

swapoff

Disables devices and files for paging and swapping

swapon

Enables devices and files for paging and swapping
and lists the devices and files currently in use

tunelp

Tunes the parameters of the line printer

ul

A filter for translating underscores into escape
sequences indicating underlining for the terminal
in use

umount

Disconnects a file system from the system's file
tree

vidmode

Sets the video mode in a bootable image

whereis

Reports the location of the binary, source, and man
page for the given command

write

Sends a message to the given user if that user has not
disabled receipt of such messages

6.60. About Debugging
Symbols

Most programs and libraries are, by default, compiled with
debugging symbols included (with gcc's -g option). This means that when
debugging a program or library that was compiled with debugging
information included, the debugger can provide not only memory
addresses, but also the names of the routines and variables.

However, the inclusion of these debugging symbols enlarges a
program or library significantly. The following is an example
of the amount of space these symbols occupy:

a bash binary with debugging symbols: 1200 KB

a bash binary without debugging symbols: 480 KB

Glibc and GCC files (/lib and
/usr/lib) with debugging
symbols: 87 MB

Glibc and GCC files without debugging symbols: 16 MB

Sizes may vary depending on which compiler and C library were
used, but when comparing programs with and without debugging
symbols, the difference will usually be a factor between two
and five.

Because most users will never use a debugger on their system
software, a lot of disk space can be regained by removing these
symbols. The next section shows how to strip all debugging
symbols from the programs and libraries. Additional information
on system optimization can be found at http://www.linuxfromscratch.org/hints/downloads/files/optimization.txt.

6.61. Stripping Again

If the intended user is not a programmer and does not plan to
do any debugging on the system software, the system size can be
decreased by about 200 MB by removing the debugging symbols
from binaries and libraries. This causes no inconvenience other
than not being able to debug the software fully anymore.

Most people who use the command mentioned below do not
experience any difficulties. However, it is easy to make a typo
and render the new system unusable, so before running the
strip command, it
is a good idea to make a backup of the current situation.

Before performing the stripping, take special care to ensure
that none of the binaries that are about to be stripped are
running. If unsure whether the user entered chroot with the
command given in Section 6.3,
“Entering the Chroot Environment,” first exit
from chroot:

The reason for this is that the programs in /tools are no longer needed. Since they are no
longer needed you can delete the /tools directory if so desired or tar it up and
keep it to build another final system.

Note

Removing /tools will also remove
the temporary copies of Tcl, Expect, and DejaGNU which were
used for running the toolchain tests. If you need these
programs later on, they will need to be recompiled and
re-installed. The BLFS book has instructions for this (see
http://www.linuxfromscratch.org/blfs/).

Chapter 7. Setting Up
System Bootscripts

7.1. Introduction

This chapter details how to install and configure the
LFS-Bootscripts package. Most of these scripts will work
without modification, but a few require additional
configuration files because they deal with hardware-dependent
information.

Short Descriptions

checkfs

Checks the integrity of the file systems before
they are mounted (with the exception of journal and
network based file systems)

cleanfs

Removes files that should not be preserved between
reboots, such as those in /var/run/ and /var/lock/; it re-creates
/var/run/utmp and removes
the possibly present /etc/nologin, /fastboot, and /forcefsck files

console

Loads the correct keymap table for the desired
keyboard layout; it also sets the screen font

functions

Contains common functions, such as error and status
checking, that are used by several bootscripts

halt

Halts the system

hotplug

Loads modules for system devices

ifdown

Assists the network script with stopping network
devices

ifup

Assists the network script with starting network
devices

localnet

Sets up the system's hostname and local loopback
device

mountfs

Mounts all file systems, except ones that are
marked noauto or are network
based